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<h1 class="settitle" align="center">GNU libgomp</h1>







<a name="SEC_Overview"></a>
<h2 class="shortcontents-heading">Short Table of Contents</h2>

<div class="shortcontents">
<ul class="no-bullet">
<li><a name="stoc-Enabling-OpenMP-1" href="#toc-Enabling-OpenMP-1">1 Enabling OpenMP</a></li>
<li><a name="stoc-Runtime-Library-Routines-1" href="#toc-Runtime-Library-Routines-1">2 Runtime Library Routines</a></li>
<li><a name="stoc-Environment-Variables-1" href="#toc-Environment-Variables-1">3 Environment Variables</a></li>
<li><a name="stoc-The-libgomp-ABI-1" href="#toc-The-libgomp-ABI-1">4 The libgomp ABI</a></li>
<li><a name="stoc-Reporting-Bugs-1" href="#toc-Reporting-Bugs-1">5 Reporting Bugs</a></li>
<li><a name="stoc-GNU-GENERAL-PUBLIC-LICENSE" href="#toc-GNU-GENERAL-PUBLIC-LICENSE">GNU GENERAL PUBLIC LICENSE</a></li>
<li><a name="stoc-GNU-Free-Documentation-License-1" href="#toc-GNU-Free-Documentation-License-1">GNU Free Documentation License</a></li>
<li><a name="stoc-Funding-Free-Software" href="#toc-Funding-Free-Software">Funding Free Software</a></li>
<li><a name="stoc-Index-1" href="#toc-Index-1">Index</a></li>
</ul>
</div>

<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="no-bullet">
  <li><a name="toc-Enabling-OpenMP-1" href="#Enabling-OpenMP">1 Enabling OpenMP</a></li>
  <li><a name="toc-Runtime-Library-Routines-1" href="#Runtime-Library-Routines">2 Runtime Library Routines</a>
  <ul class="no-bullet">
    <li><a name="toc-omp_005fget_005factive_005flevel-_002d_002d-Number-of-parallel-regions" href="#omp_005fget_005factive_005flevel">2.1 <code>omp_get_active_level</code> &ndash; Number of parallel regions</a></li>
    <li><a name="toc-omp_005fget_005fancestor_005fthread_005fnum-_002d_002d-Ancestor-thread-ID" href="#omp_005fget_005fancestor_005fthread_005fnum">2.2 <code>omp_get_ancestor_thread_num</code> &ndash; Ancestor thread ID</a></li>
    <li><a name="toc-omp_005fget_005fdynamic-_002d_002d-Dynamic-teams-setting" href="#omp_005fget_005fdynamic">2.3 <code>omp_get_dynamic</code> &ndash; Dynamic teams setting</a></li>
    <li><a name="toc-omp_005fget_005flevel-_002d_002d-Obtain-the-current-nesting-level" href="#omp_005fget_005flevel">2.4 <code>omp_get_level</code> &ndash; Obtain the current nesting level</a></li>
    <li><a name="toc-omp_005fget_005fmax_005factive_005flevels-_002d_002d-Maximum-number-of-active-regions" href="#omp_005fget_005fmax_005factive_005flevels">2.5 <code>omp_get_max_active_levels</code> &ndash; Maximum number of active regions</a></li>
    <li><a name="toc-omp_005fget_005fmax_005fthreads-_002d_002d-Maximum-number-of-threads-of-parallel-region" href="#omp_005fget_005fmax_005fthreads">2.6 <code>omp_get_max_threads</code> &ndash; Maximum number of threads of parallel region</a></li>
    <li><a name="toc-omp_005fget_005fnested-_002d_002d-Nested-parallel-regions" href="#omp_005fget_005fnested">2.7 <code>omp_get_nested</code> &ndash; Nested parallel regions</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fprocs-_002d_002d-Number-of-processors-online" href="#omp_005fget_005fnum_005fprocs">2.8 <code>omp_get_num_procs</code> &ndash; Number of processors online</a></li>
    <li><a name="toc-omp_005fget_005fnum_005fthreads-_002d_002d-Size-of-the-active-team" href="#omp_005fget_005fnum_005fthreads">2.9 <code>omp_get_num_threads</code> &ndash; Size of the active team</a></li>
    <li><a name="toc-omp_005fget_005fschedule-_002d_002d-Obtain-the-runtime-scheduling-method" href="#omp_005fget_005fschedule">2.10 <code>omp_get_schedule</code> &ndash; Obtain the runtime scheduling method</a></li>
    <li><a name="toc-omp_005fget_005fteam_005fsize-_002d_002d-Number-of-threads-in-a-team" href="#omp_005fget_005fteam_005fsize">2.11 <code>omp_get_team_size</code> &ndash; Number of threads in a team</a></li>
    <li><a name="toc-omp_005fget_005fthread_005flimit-_002d_002d-Maximum-number-of-threads" href="#omp_005fget_005fthread_005flimit">2.12 <code>omp_get_thread_limit</code> &ndash; Maximum number of threads</a></li>
    <li><a name="toc-omp_005fget_005fthread_005fnum-_002d_002d-Current-thread-ID" href="#omp_005fget_005fthread_005fnum">2.13 <code>omp_get_thread_num</code> &ndash; Current thread ID</a></li>
    <li><a name="toc-omp_005fin_005fparallel-_002d_002d-Whether-a-parallel-region-is-active" href="#omp_005fin_005fparallel">2.14 <code>omp_in_parallel</code> &ndash; Whether a parallel region is active</a></li>
    <li><a name="toc-omp_005fin_005ffinal-_002d_002d-Whether-in-final-or-included-task-region" href="#omp_005fin_005ffinal">2.15 <code>omp_in_final</code> &ndash; Whether in final or included task region</a></li>
    <li><a name="toc-omp_005fset_005fdynamic-_002d_002d-Enable_002fdisable-dynamic-teams" href="#omp_005fset_005fdynamic">2.16 <code>omp_set_dynamic</code> &ndash; Enable/disable dynamic teams</a></li>
    <li><a name="toc-omp_005fset_005fmax_005factive_005flevels-_002d_002d-Limits-the-number-of-active-parallel-regions" href="#omp_005fset_005fmax_005factive_005flevels">2.17 <code>omp_set_max_active_levels</code> &ndash; Limits the number of active parallel regions</a></li>
    <li><a name="toc-omp_005fset_005fnested-_002d_002d-Enable_002fdisable-nested-parallel-regions" href="#omp_005fset_005fnested">2.18 <code>omp_set_nested</code> &ndash; Enable/disable nested parallel regions</a></li>
    <li><a name="toc-omp_005fset_005fnum_005fthreads-_002d_002d-Set-upper-team-size-limit" href="#omp_005fset_005fnum_005fthreads">2.19 <code>omp_set_num_threads</code> &ndash; Set upper team size limit</a></li>
    <li><a name="toc-omp_005fset_005fschedule-_002d_002d-Set-the-runtime-scheduling-method" href="#omp_005fset_005fschedule">2.20 <code>omp_set_schedule</code> &ndash; Set the runtime scheduling method</a></li>
    <li><a name="toc-omp_005finit_005flock-_002d_002d-Initialize-simple-lock" href="#omp_005finit_005flock">2.21 <code>omp_init_lock</code> &ndash; Initialize simple lock</a></li>
    <li><a name="toc-omp_005fset_005flock-_002d_002d-Wait-for-and-set-simple-lock" href="#omp_005fset_005flock">2.22 <code>omp_set_lock</code> &ndash; Wait for and set simple lock</a></li>
    <li><a name="toc-omp_005ftest_005flock-_002d_002d-Test-and-set-simple-lock-if-available" href="#omp_005ftest_005flock">2.23 <code>omp_test_lock</code> &ndash; Test and set simple lock if available</a></li>
    <li><a name="toc-omp_005funset_005flock-_002d_002d-Unset-simple-lock" href="#omp_005funset_005flock">2.24 <code>omp_unset_lock</code> &ndash; Unset simple lock</a></li>
    <li><a name="toc-omp_005fdestroy_005flock-_002d_002d-Destroy-simple-lock" href="#omp_005fdestroy_005flock">2.25 <code>omp_destroy_lock</code> &ndash; Destroy simple lock</a></li>
    <li><a name="toc-omp_005finit_005fnest_005flock-_002d_002d-Initialize-nested-lock" href="#omp_005finit_005fnest_005flock">2.26 <code>omp_init_nest_lock</code> &ndash; Initialize nested lock</a></li>
    <li><a name="toc-omp_005fset_005fnest_005flock-_002d_002d-Wait-for-and-set-nested-lock" href="#omp_005fset_005fnest_005flock">2.27 <code>omp_set_nest_lock</code> &ndash; Wait for and set nested lock</a></li>
    <li><a name="toc-omp_005ftest_005fnest_005flock-_002d_002d-Test-and-set-nested-lock-if-available" href="#omp_005ftest_005fnest_005flock">2.28 <code>omp_test_nest_lock</code> &ndash; Test and set nested lock if available</a></li>
    <li><a name="toc-omp_005funset_005fnest_005flock-_002d_002d-Unset-nested-lock" href="#omp_005funset_005fnest_005flock">2.29 <code>omp_unset_nest_lock</code> &ndash; Unset nested lock</a></li>
    <li><a name="toc-omp_005fdestroy_005fnest_005flock-_002d_002d-Destroy-nested-lock" href="#omp_005fdestroy_005fnest_005flock">2.30 <code>omp_destroy_nest_lock</code> &ndash; Destroy nested lock</a></li>
    <li><a name="toc-omp_005fget_005fwtick-_002d_002d-Get-timer-precision" href="#omp_005fget_005fwtick">2.31 <code>omp_get_wtick</code> &ndash; Get timer precision</a></li>
    <li><a name="toc-omp_005fget_005fwtime-_002d_002d-Elapsed-wall-clock-time" href="#omp_005fget_005fwtime">2.32 <code>omp_get_wtime</code> &ndash; Elapsed wall clock time</a></li>
  </ul></li>
  <li><a name="toc-Environment-Variables-1" href="#Environment-Variables">3 Environment Variables</a>
  <ul class="no-bullet">
    <li><a name="toc-OMP_005fDYNAMIC-_002d_002d-Dynamic-adjustment-of-threads" href="#OMP_005fDYNAMIC">3.1 <code>OMP_DYNAMIC</code> &ndash; Dynamic adjustment of threads</a></li>
    <li><a name="toc-OMP_005fMAX_005fACTIVE_005fLEVELS-_002d_002d-Set-the-maximum-number-of-nested-parallel-regions" href="#OMP_005fMAX_005fACTIVE_005fLEVELS">3.2 <code>OMP_MAX_ACTIVE_LEVELS</code> &ndash; Set the maximum number of nested parallel regions</a></li>
    <li><a name="toc-OMP_005fNESTED-_002d_002d-Nested-parallel-regions" href="#OMP_005fNESTED">3.3 <code>OMP_NESTED</code> &ndash; Nested parallel regions</a></li>
    <li><a name="toc-OMP_005fNUM_005fTHREADS-_002d_002d-Specifies-the-number-of-threads-to-use" href="#OMP_005fNUM_005fTHREADS">3.4 <code>OMP_NUM_THREADS</code> &ndash; Specifies the number of threads to use</a></li>
    <li><a name="toc-OMP_005fSCHEDULE-_002d_002d-How-threads-are-scheduled" href="#OMP_005fSCHEDULE">3.5 <code>OMP_SCHEDULE</code> &ndash; How threads are scheduled</a></li>
    <li><a name="toc-OMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size" href="#OMP_005fSTACKSIZE">3.6 <code>OMP_STACKSIZE</code> &ndash; Set default thread stack size</a></li>
    <li><a name="toc-OMP_005fTHREAD_005fLIMIT-_002d_002d-Set-the-maximum-number-of-threads" href="#OMP_005fTHREAD_005fLIMIT">3.7 <code>OMP_THREAD_LIMIT</code> &ndash; Set the maximum number of threads</a></li>
    <li><a name="toc-OMP_005fWAIT_005fPOLICY-_002d_002d-How-waiting-threads-are-handled" href="#OMP_005fWAIT_005fPOLICY">3.8 <code>OMP_WAIT_POLICY</code> &ndash; How waiting threads are handled</a></li>
    <li><a name="toc-OMP_005fPROC_005fBIND-_002d_002d-Whether-theads-may-be-moved-between-CPUs" href="#OMP_005fPROC_005fBIND">3.9 <code>OMP_PROC_BIND</code> &ndash; Whether theads may be moved between CPUs</a></li>
    <li><a name="toc-GOMP_005fCPU_005fAFFINITY-_002d_002d-Bind-threads-to-specific-CPUs" href="#GOMP_005fCPU_005fAFFINITY">3.10 <code>GOMP_CPU_AFFINITY</code> &ndash; Bind threads to specific CPUs</a></li>
    <li><a name="toc-GOMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size" href="#GOMP_005fSTACKSIZE">3.11 <code>GOMP_STACKSIZE</code> &ndash; Set default thread stack size</a></li>
  </ul></li>
  <li><a name="toc-The-libgomp-ABI-1" href="#The-libgomp-ABI">4 The libgomp ABI</a>
  <ul class="no-bullet">
    <li><a name="toc-Implementing-MASTER-construct-1" href="#Implementing-MASTER-construct">4.1 Implementing MASTER construct</a></li>
    <li><a name="toc-Implementing-CRITICAL-construct-1" href="#Implementing-CRITICAL-construct">4.2 Implementing CRITICAL construct</a></li>
    <li><a name="toc-Implementing-ATOMIC-construct-1" href="#Implementing-ATOMIC-construct">4.3 Implementing ATOMIC construct</a></li>
    <li><a name="toc-Implementing-FLUSH-construct-1" href="#Implementing-FLUSH-construct">4.4 Implementing FLUSH construct</a></li>
    <li><a name="toc-Implementing-BARRIER-construct-1" href="#Implementing-BARRIER-construct">4.5 Implementing BARRIER construct</a></li>
    <li><a name="toc-Implementing-THREADPRIVATE-construct-1" href="#Implementing-THREADPRIVATE-construct">4.6 Implementing THREADPRIVATE construct</a></li>
    <li><a name="toc-Implementing-PRIVATE-clause-1" href="#Implementing-PRIVATE-clause">4.7 Implementing PRIVATE clause</a></li>
    <li><a name="toc-Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1" href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses">4.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a></li>
    <li><a name="toc-Implementing-REDUCTION-clause-1" href="#Implementing-REDUCTION-clause">4.9 Implementing REDUCTION clause</a></li>
    <li><a name="toc-Implementing-PARALLEL-construct-1" href="#Implementing-PARALLEL-construct">4.10 Implementing PARALLEL construct</a></li>
    <li><a name="toc-Implementing-FOR-construct-1" href="#Implementing-FOR-construct">4.11 Implementing FOR construct</a></li>
    <li><a name="toc-Implementing-ORDERED-construct-1" href="#Implementing-ORDERED-construct">4.12 Implementing ORDERED construct</a></li>
    <li><a name="toc-Implementing-SECTIONS-construct-1" href="#Implementing-SECTIONS-construct">4.13 Implementing SECTIONS construct</a></li>
    <li><a name="toc-Implementing-SINGLE-construct-1" href="#Implementing-SINGLE-construct">4.14 Implementing SINGLE construct</a></li>
  </ul></li>
  <li><a name="toc-Reporting-Bugs-1" href="#Reporting-Bugs">5 Reporting Bugs</a></li>
  <li><a name="toc-GNU-GENERAL-PUBLIC-LICENSE" href="#Copying">GNU GENERAL PUBLIC LICENSE</a>
  <ul class="no-bullet">
    <li><a name="toc-Preamble" href="#Preamble">Preamble</a></li>
    <li><a name="toc-Appendix_003a-How-to-Apply-These-Terms-to-Your-New-Programs" href="#Appendix_003a-How-to-Apply-These-Terms-to-Your-New-Programs">Appendix: How to Apply These Terms to Your New Programs</a></li>
  </ul></li>
  <li><a name="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">GNU Free Documentation License</a>
  <ul class="no-bullet">
    <li><a name="toc-ADDENDUM_003a-How-to-use-this-License-for-your-documents" href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</a></li>
  </ul></li>
  <li><a name="toc-Funding-Free-Software" href="#Funding">Funding Free Software</a></li>
  <li><a name="toc-Index-1" href="#Index">Index</a></li>
</ul>
</div>



<a name="Top"></a>
<div class="header">
<p>
Next: <a href="#Enabling-OpenMP" accesskey="n" rel="next">Enabling OpenMP</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Introduction"></a>
<h1 class="top">Introduction</h1>
<a name="index-Introduction"></a>

<p>This manual documents the usage of libgomp, the GNU implementation of the 
<a href="http://www.openmp.org">OpenMP</a> Application Programming Interface (API)
for multi-platform shared-memory parallel programming in C/C++ and Fortran.
</p>


<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Enabling-OpenMP" accesskey="1">Enabling OpenMP</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to enable OpenMP for your applications.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Runtime-Library-Routines" accesskey="2">Runtime Library Routines</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">The OpenMP runtime application programming 
                               interface.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Environment-Variables" accesskey="3">Environment Variables</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Influencing runtime behavior with environment 
                               variables.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-libgomp-ABI" accesskey="4">The libgomp ABI</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Notes on the external ABI presented by libgomp.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Reporting-Bugs" accesskey="5">Reporting Bugs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to report bugs in GNU OpenMP.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Copying" accesskey="6">Copying</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">GNU general public license says
                               how you can copy and share libgomp.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GNU-Free-Documentation-License" accesskey="7">GNU Free Documentation License</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
                               How you can copy and share this manual.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Funding" accesskey="8">Funding</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How to help assure continued work for free 
                               software.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Index" accesskey="9">Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Index of this documentation.
</td></tr>
</table>



<hr>
<a name="Enabling-OpenMP"></a>
<div class="header">
<p>
Next: <a href="#Runtime-Library-Routines" accesskey="n" rel="next">Runtime Library Routines</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Enabling-OpenMP-1"></a>
<h2 class="chapter">1 Enabling OpenMP</h2>

<p>To activate the OpenMP extensions for C/C++ and Fortran, the compile-time 
flag <code>-fopenmp</code> must be specified. This enables the OpenMP directive
<code>#pragma omp</code> in C/C++ and <code>!$omp</code> directives in free form, 
<code>c$omp</code>, <code>*$omp</code> and <code>!$omp</code> directives in fixed form, 
<code>!$</code> conditional compilation sentinels in free form and <code>c$</code>,
<code>*$</code> and <code>!$</code> sentinels in fixed form, for Fortran. The flag also
arranges for automatic linking of the OpenMP runtime library 
(<a href="#Runtime-Library-Routines">Runtime Library Routines</a>).
</p>
<p>A complete description of all OpenMP directives accepted may be found in 
the <a href="http://www.openmp.org">OpenMP Application Program Interface</a> manual,
version 3.1.
</p>


<hr>
<a name="Runtime-Library-Routines"></a>
<div class="header">
<p>
Next: <a href="#Environment-Variables" accesskey="n" rel="next">Environment Variables</a>, Previous: <a href="#Enabling-OpenMP" accesskey="p" rel="prev">Enabling OpenMP</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Runtime-Library-Routines-1"></a>
<h2 class="chapter">2 Runtime Library Routines</h2>

<p>The runtime routines described here are defined by section 3 of the OpenMP 
specifications in version 3.1. The routines are structured in following
three parts:
</p>
<p>Control threads, processors and the parallel environment.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005factive_005flevel" accesskey="1">omp_get_active_level</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of active parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="2">omp_get_ancestor_thread_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Ancestor thread ID
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fdynamic" accesskey="3">omp_get_dynamic</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Dynamic teams setting
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005flevel" accesskey="4">omp_get_level</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="5">omp_get_max_active_levels</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of active regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fmax_005fthreads" accesskey="6">omp_get_max_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of threads of parallel region
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnested" accesskey="7">omp_get_nested</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fprocs" accesskey="8">omp_get_num_procs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of processors online
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fnum_005fthreads" accesskey="9">omp_get_num_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Size of the active team
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fschedule">omp_get_schedule</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Obtain the runtime scheduling method
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fteam_005fsize">omp_get_team_size</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Number of threads in a team
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Maximum number of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fthread_005fnum">omp_get_thread_num</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Current thread ID
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fin_005fparallel">omp_in_parallel</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether a parallel region is active
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fin_005ffinal">omp_in_final</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether in final or included task region
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable/disable dynamic teams
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Limits the number of active parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnested">omp_set_nested</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable/disable nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set upper team size limit
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fschedule">omp_set_schedule</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the runtime scheduling method
</td></tr>
</table>

<p>Initialize, set, test, unset and destroy simple and nested locks.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#omp_005finit_005flock" accesskey="1">omp_init_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Initialize simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005flock" accesskey="2">omp_set_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for and set simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005ftest_005flock" accesskey="3">omp_test_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Test and set simple lock if available
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005funset_005flock" accesskey="4">omp_unset_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Unset simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fdestroy_005flock" accesskey="5">omp_destroy_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Destroy simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005finit_005fnest_005flock" accesskey="6">omp_init_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Initialize nested lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fset_005fnest_005flock" accesskey="7">omp_set_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Wait for and set simple lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005ftest_005fnest_005flock" accesskey="8">omp_test_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Test and set nested lock if available
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005funset_005fnest_005flock" accesskey="9">omp_unset_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Unset nested lock
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fdestroy_005fnest_005flock">omp_destroy_nest_lock</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Destroy nested lock
</td></tr>
</table>

<p>Portable, thread-based, wall clock timer.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fwtick" accesskey="1">omp_get_wtick</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Get timer precision.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#omp_005fget_005fwtime" accesskey="2">omp_get_wtime</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Elapsed wall clock time.
</td></tr>
</table>



<hr>
<a name="omp_005fget_005factive_005flevel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="n" rel="next">omp_get_ancestor_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005factive_005flevel-_002d_002d-Number-of-parallel-regions"></a>
<h3 class="section">2.1 <code>omp_get_active_level</code> &ndash; Number of parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the nesting level for the active parallel blocks,
which enclose the calling call.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_active_level(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_active_level()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fmax_005factive_005flevels">omp_get_max_active_levels</a>, <a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.19.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fancestor_005fthread_005fnum"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fdynamic" accesskey="n" rel="next">omp_get_dynamic</a>, Previous: <a href="#omp_005fget_005factive_005flevel" accesskey="p" rel="prev">omp_get_active_level</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fancestor_005fthread_005fnum-_002d_002d-Ancestor-thread-ID"></a>
<h3 class="section">2.2 <code>omp_get_ancestor_thread_num</code> &ndash; Ancestor thread ID</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the thread identification number for the given
nesting level of the current thread. For values of <var>level</var> outside
zero to <code>omp_get_level</code> -1 is returned; if <var>level</var> is
<code>omp_get_level</code> the result is identical to <code>omp_get_thread_num</code>.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_ancestor_thread_num(int level);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_ancestor_thread_num(level)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer level</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fthread_005fnum">omp_get_thread_num</a>, <a href="#omp_005fget_005fteam_005fsize">omp_get_team_size</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.17.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fdynamic"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005flevel" accesskey="n" rel="next">omp_get_level</a>, Previous: <a href="#omp_005fget_005fancestor_005fthread_005fnum" accesskey="p" rel="prev">omp_get_ancestor_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fdynamic-_002d_002d-Dynamic-teams-setting"></a>
<h3 class="section">2.3 <code>omp_get_dynamic</code> &ndash; Dynamic teams setting</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if enabled, <code>false</code> otherwise. 
Here, <code>true</code> and <code>false</code> represent their language-specific 
counterparts.
</p>
<p>The dynamic team setting may be initialized at startup by the 
<code>OMP_DYNAMIC</code> environment variable or at runtime using 
<code>omp_set_dynamic</code>. If undefined, dynamic adjustment is 
disabled by default.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_dynamic(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_get_dynamic()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>, <a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.8.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005flevel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="n" rel="next">omp_get_max_active_levels</a>, Previous: <a href="#omp_005fget_005fdynamic" accesskey="p" rel="prev">omp_get_dynamic</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005flevel-_002d_002d-Obtain-the-current-nesting-level"></a>
<h3 class="section">2.4 <code>omp_get_level</code> &ndash; Obtain the current nesting level</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the nesting level for the parallel blocks,
which enclose the calling call.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_level(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_level()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.16.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fmax_005factive_005flevels"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fmax_005fthreads" accesskey="n" rel="next">omp_get_max_threads</a>, Previous: <a href="#omp_005fget_005flevel" accesskey="p" rel="prev">omp_get_level</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fmax_005factive_005flevels-_002d_002d-Maximum-number-of-active-regions"></a>
<h3 class="section">2.5 <code>omp_get_max_active_levels</code> &ndash; Maximum number of active regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function obtains the maximum allowed number of nested, active parallel regions.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_max_active_levels(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_max_active_levels()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>, <a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.15.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fmax_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnested" accesskey="n" rel="next">omp_get_nested</a>, Previous: <a href="#omp_005fget_005fmax_005factive_005flevels" accesskey="p" rel="prev">omp_get_max_active_levels</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fmax_005fthreads-_002d_002d-Maximum-number-of-threads-of-parallel-region"></a>
<h3 class="section">2.6 <code>omp_get_max_threads</code> &ndash; Maximum number of threads of parallel region</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Return the maximum number of threads used for the current parallel region
that does not use the clause <code>num_threads</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_max_threads(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_max_threads()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>, <a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>, <a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.3.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnested"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fprocs" accesskey="n" rel="next">omp_get_num_procs</a>, Previous: <a href="#omp_005fget_005fmax_005fthreads" accesskey="p" rel="prev">omp_get_max_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnested-_002d_002d-Nested-parallel-regions"></a>
<h3 class="section">2.7 <code>omp_get_nested</code> &ndash; Nested parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if nested parallel regions are
enabled, <code>false</code> otherwise. Here, <code>true</code> and <code>false</code> 
represent their language-specific counterparts.
</p>
<p>Nested parallel regions may be initialized at startup by the 
<code>OMP_NESTED</code> environment variable or at runtime using 
<code>omp_set_nested</code>. If undefined, nested parallel regions are
disabled by default.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_nested(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_get_nested()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnested">omp_set_nested</a>, <a href="#OMP_005fNESTED">OMP_NESTED</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.10.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fprocs"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fnum_005fthreads" accesskey="n" rel="next">omp_get_num_threads</a>, Previous: <a href="#omp_005fget_005fnested" accesskey="p" rel="prev">omp_get_nested</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fprocs-_002d_002d-Number-of-processors-online"></a>
<h3 class="section">2.8 <code>omp_get_num_procs</code> &ndash; Number of processors online</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of processors online.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_procs(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_procs()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.5.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fnum_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fschedule" accesskey="n" rel="next">omp_get_schedule</a>, Previous: <a href="#omp_005fget_005fnum_005fprocs" accesskey="p" rel="prev">omp_get_num_procs</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fnum_005fthreads-_002d_002d-Size-of-the-active-team"></a>
<h3 class="section">2.9 <code>omp_get_num_threads</code> &ndash; Size of the active team</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns the number of threads in the current team. In a sequential section of 
the program <code>omp_get_num_threads</code> returns 1.
</p>
<p>The default team size may be initialized at startup by the 
<code>OMP_NUM_THREADS</code> environment variable. At runtime, the size 
of the current team may be set either by the <code>NUM_THREADS</code>
clause or by <code>omp_set_num_threads</code>. If none of the above were 
used to define a specific value and <code>OMP_DYNAMIC</code> is disabled,
one thread per CPU online is used.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_num_threads(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_num_threads()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>, <a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>, <a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.2.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fschedule"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fteam_005fsize" accesskey="n" rel="next">omp_get_team_size</a>, Previous: <a href="#omp_005fget_005fnum_005fthreads" accesskey="p" rel="prev">omp_get_num_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fschedule-_002d_002d-Obtain-the-runtime-scheduling-method"></a>
<h3 class="section">2.10 <code>omp_get_schedule</code> &ndash; Obtain the runtime scheduling method</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Obtain the runtime scheduling method. The <var>kind</var> argument will be
set to the value <code>omp_sched_static</code>, <code>omp_sched_dynamic</code>,
<code>omp_sched_guided</code> or <code>omp_sched_auto</code>. The second argument,
<var>modifier</var>, is set to the chunk size.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_schedule(omp_sched_t *kind, int *modifier);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_schedule(kind, modifier)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=omp_sched_kind) kind</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer modifier</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fschedule">omp_set_schedule</a>, <a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.12.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fteam_005fsize"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fthread_005flimit" accesskey="n" rel="next">omp_get_thread_limit</a>, Previous: <a href="#omp_005fget_005fschedule" accesskey="p" rel="prev">omp_get_schedule</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fteam_005fsize-_002d_002d-Number-of-threads-in-a-team"></a>
<h3 class="section">2.11 <code>omp_get_team_size</code> &ndash; Number of threads in a team</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns the number of threads in a thread team to which
either the current thread or its ancestor belongs. For values of <var>level</var>
outside zero to <code>omp_get_level</code>, -1 is returned; if <var>level</var> is zero,
1 is returned, and for <code>omp_get_level</code>, the result is identical
to <code>omp_get_num_threads</code>.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_team_size(int level);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_team_size(level)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer level</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005flevel">omp_get_level</a>, <a href="#omp_005fget_005fancestor_005fthread_005fnum">omp_get_ancestor_thread_num</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.18.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fthread_005flimit"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fthread_005fnum" accesskey="n" rel="next">omp_get_thread_num</a>, Previous: <a href="#omp_005fget_005fteam_005fsize" accesskey="p" rel="prev">omp_get_team_size</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fthread_005flimit-_002d_002d-Maximum-number-of-threads"></a>
<h3 class="section">2.12 <code>omp_get_thread_limit</code> &ndash; Maximum number of threads</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Return the maximum number of threads of the program.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_thread_limit(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_thread_limit()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>, <a href="#OMP_005fTHREAD_005fLIMIT">OMP_THREAD_LIMIT</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.13.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fthread_005fnum"></a>
<div class="header">
<p>
Next: <a href="#omp_005fin_005fparallel" accesskey="n" rel="next">omp_in_parallel</a>, Previous: <a href="#omp_005fget_005fthread_005flimit" accesskey="p" rel="prev">omp_get_thread_limit</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fthread_005fnum-_002d_002d-Current-thread-ID"></a>
<h3 class="section">2.13 <code>omp_get_thread_num</code> &ndash; Current thread ID</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Returns a unique thread identification number within the current team.
In a sequential parts of the program, <code>omp_get_thread_num</code>
always returns 0. In parallel regions the return value varies
from 0 to <code>omp_get_num_threads</code>-1 inclusive. The return 
value of the master thread of a team is always 0.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_get_thread_num(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>integer function omp_get_thread_num()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005fancestor_005fthread_005fnum">omp_get_ancestor_thread_num</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.4.
</p></dd>
</dl>



<hr>
<a name="omp_005fin_005fparallel"></a>
<div class="header">
<p>
Next: <a href="#omp_005fin_005ffinal" accesskey="n" rel="next">omp_in_final</a>, Previous: <a href="#omp_005fget_005fthread_005fnum" accesskey="p" rel="prev">omp_get_thread_num</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fin_005fparallel-_002d_002d-Whether-a-parallel-region-is-active"></a>
<h3 class="section">2.14 <code>omp_in_parallel</code> &ndash; Whether a parallel region is active</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if currently running in parallel, 
<code>false</code> otherwise. Here, <code>true</code> and <code>false</code> represent 
their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_in_parallel(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_in_parallel()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.6.
</p></dd>
</dl>


<hr>
<a name="omp_005fin_005ffinal"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fdynamic" accesskey="n" rel="next">omp_set_dynamic</a>, Previous: <a href="#omp_005fin_005fparallel" accesskey="p" rel="prev">omp_in_parallel</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fin_005ffinal-_002d_002d-Whether-in-final-or-included-task-region"></a>
<h3 class="section">2.15 <code>omp_in_final</code> &ndash; Whether in final or included task region</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function returns <code>true</code> if currently running in a final
or included task region, <code>false</code> otherwise. Here, <code>true</code>
and <code>false</code> represent their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_in_final(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_in_final()</code></td></tr>
</table>

</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.20.
</p></dd>
</dl>


<hr>
<a name="omp_005fset_005fdynamic"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fmax_005factive_005flevels" accesskey="n" rel="next">omp_set_max_active_levels</a>, Previous: <a href="#omp_005fin_005ffinal" accesskey="p" rel="prev">omp_in_final</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fdynamic-_002d_002d-Enable_002fdisable-dynamic-teams"></a>
<h3 class="section">2.16 <code>omp_set_dynamic</code> &ndash; Enable/disable dynamic teams</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable the dynamic adjustment of the number of threads 
within a team. The function takes the language-specific equivalent
of <code>true</code> and <code>false</code>, where <code>true</code> enables dynamic 
adjustment of team sizes and <code>false</code> disables it.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_dynamic(int set);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_dynamic(set)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical, intent(in) :: set</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a>, <a href="#omp_005fget_005fdynamic">omp_get_dynamic</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.7.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fmax_005factive_005flevels"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnested" accesskey="n" rel="next">omp_set_nested</a>, Previous: <a href="#omp_005fset_005fdynamic" accesskey="p" rel="prev">omp_set_dynamic</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fmax_005factive_005flevels-_002d_002d-Limits-the-number-of-active-parallel-regions"></a>
<h3 class="section">2.17 <code>omp_set_max_active_levels</code> &ndash; Limits the number of active parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>This function limits the maximum allowed number of nested, active
parallel regions.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_max_active_levels(int max_levels);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_max_active_levels(max_levels)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer max_levels</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fmax_005factive_005flevels">omp_get_max_active_levels</a>, <a href="#omp_005fget_005factive_005flevel">omp_get_active_level</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.14.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fnested"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnum_005fthreads" accesskey="n" rel="next">omp_set_num_threads</a>, Previous: <a href="#omp_005fset_005fmax_005factive_005flevels" accesskey="p" rel="prev">omp_set_max_active_levels</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnested-_002d_002d-Enable_002fdisable-nested-parallel-regions"></a>
<h3 class="section">2.18 <code>omp_set_nested</code> &ndash; Enable/disable nested parallel regions</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable nested parallel regions, i.e., whether team members
are allowed to create new teams. The function takes the language-specific 
equivalent of <code>true</code> and <code>false</code>, where <code>true</code> enables 
dynamic adjustment of team sizes and <code>false</code> disables it.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_nested(int set);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_nested(set)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>logical, intent(in) :: set</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNESTED">OMP_NESTED</a>, <a href="#omp_005fget_005fnested">omp_get_nested</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.9.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fnum_005fthreads"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fschedule" accesskey="n" rel="next">omp_set_schedule</a>, Previous: <a href="#omp_005fset_005fnested" accesskey="p" rel="prev">omp_set_nested</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnum_005fthreads-_002d_002d-Set-upper-team-size-limit"></a>
<h3 class="section">2.19 <code>omp_set_num_threads</code> &ndash; Set upper team size limit</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the number of threads used by default in subsequent parallel 
sections, if those do not specify a <code>num_threads</code> clause. The 
argument of <code>omp_set_num_threads</code> shall be a positive integer. 
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_num_threads(int n);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_num_threads(n)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer, intent(in) :: n</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>, <a href="#omp_005fget_005fnum_005fthreads">omp_get_num_threads</a>, <a href="#omp_005fget_005fmax_005fthreads">omp_get_max_threads</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.1.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005fschedule"></a>
<div class="header">
<p>
Next: <a href="#omp_005finit_005flock" accesskey="n" rel="next">omp_init_lock</a>, Previous: <a href="#omp_005fset_005fnum_005fthreads" accesskey="p" rel="prev">omp_set_num_threads</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fschedule-_002d_002d-Set-the-runtime-scheduling-method"></a>
<h3 class="section">2.20 <code>omp_set_schedule</code> &ndash; Set the runtime scheduling method</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Sets the runtime scheduling method. The <var>kind</var> argument can have the
value <code>omp_sched_static</code>, <code>omp_sched_dynamic</code>,
<code>omp_sched_guided</code> or <code>omp_sched_auto</code>. Except for
<code>omp_sched_auto</code>, the chunk size is set to the value of
<var>modifier</var> if positive, or to the default value if zero or negative.
For <code>omp_sched_auto</code> the <var>modifier</var> argument is ignored.
</p>
</dd>
<dt><em>C/C++</em></dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_schedule(omp_sched_t *kind, int *modifier);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_schedule(kind, modifier)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(kind=omp_sched_kind) kind</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer modifier</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fschedule">omp_get_schedule</a>
<a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.2.11.
</p></dd>
</dl>



<hr>
<a name="omp_005finit_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005flock" accesskey="n" rel="next">omp_set_lock</a>, Previous: <a href="#omp_005fset_005fschedule" accesskey="p" rel="prev">omp_set_schedule</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005finit_005flock-_002d_002d-Initialize-simple-lock"></a>
<h3 class="section">2.21 <code>omp_init_lock</code> &ndash; Initialize simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Initialize a simple lock.  After initialization, the lock is in 
an unlocked state.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_init_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_init_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(out) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fdestroy_005flock">omp_destroy_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.1.
</p></dd>
</dl>



<hr>
<a name="omp_005fset_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005ftest_005flock" accesskey="n" rel="next">omp_test_lock</a>, Previous: <a href="#omp_005finit_005flock" accesskey="p" rel="prev">omp_init_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005flock-_002d_002d-Wait-for-and-set-simple-lock"></a>
<h3 class="section">2.22 <code>omp_set_lock</code> &ndash; Wait for and set simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a simple lock, the lock variable must be initialized by 
<code>omp_init_lock</code>. The calling thread is blocked until the lock 
is available. If the lock is already held by the current thread, 
a deadlock occurs.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005ftest_005flock">omp_test_lock</a>, <a href="#omp_005funset_005flock">omp_unset_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.3.
</p></dd>
</dl>



<hr>
<a name="omp_005ftest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005funset_005flock" accesskey="n" rel="next">omp_unset_lock</a>, Previous: <a href="#omp_005fset_005flock" accesskey="p" rel="prev">omp_set_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005ftest_005flock-_002d_002d-Test-and-set-simple-lock-if-available"></a>
<h3 class="section">2.23 <code>omp_test_lock</code> &ndash; Test and set simple lock if available</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a simple lock, the lock variable must be initialized by 
<code>omp_init_lock</code>. Contrary to <code>omp_set_lock</code>, <code>omp_test_lock</code> 
does not block if the lock is not available. This function returns 
<code>true</code> upon success, <code>false</code> otherwise. Here, <code>true</code> and 
<code>false</code> represent their language-specific counterparts.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_test_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_test_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.5.
</p></dd>
</dl>



<hr>
<a name="omp_005funset_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fdestroy_005flock" accesskey="n" rel="next">omp_destroy_lock</a>, Previous: <a href="#omp_005ftest_005flock" accesskey="p" rel="prev">omp_test_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005funset_005flock-_002d_002d-Unset-simple-lock"></a>
<h3 class="section">2.24 <code>omp_unset_lock</code> &ndash; Unset simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>A simple lock about to be unset must have been locked by <code>omp_set_lock</code>
or <code>omp_test_lock</code> before. In addition, the lock must be held by the 
thread calling <code>omp_unset_lock</code>. Then, the lock becomes unlocked. If one 
or more threads attempted to set the lock before, one of them is chosen to, 
again, set the lock to itself.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_unset_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_unset_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005ftest_005flock">omp_test_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.4.
</p></dd>
</dl>



<hr>
<a name="omp_005fdestroy_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005finit_005fnest_005flock" accesskey="n" rel="next">omp_init_nest_lock</a>, Previous: <a href="#omp_005funset_005flock" accesskey="p" rel="prev">omp_unset_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fdestroy_005flock-_002d_002d-Destroy-simple-lock"></a>
<h3 class="section">2.25 <code>omp_destroy_lock</code> &ndash; Destroy simple lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Destroy a simple lock. In order to be destroyed, a simple lock must be 
in the unlocked state. 
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_destroy_lock(omp_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_destroy_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.2.
</p></dd>
</dl>



<hr>
<a name="omp_005finit_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fset_005fnest_005flock" accesskey="n" rel="next">omp_set_nest_lock</a>, Previous: <a href="#omp_005fdestroy_005flock" accesskey="p" rel="prev">omp_destroy_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005finit_005fnest_005flock-_002d_002d-Initialize-nested-lock"></a>
<h3 class="section">2.26 <code>omp_init_nest_lock</code> &ndash; Initialize nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Initialize a nested lock.  After initialization, the lock is in 
an unlocked state and the nesting count is set to zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_init_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_init_nest_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(out) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fdestroy_005fnest_005flock">omp_destroy_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.1.
</p></dd>
</dl>


<hr>
<a name="omp_005fset_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005ftest_005fnest_005flock" accesskey="n" rel="next">omp_test_nest_lock</a>, Previous: <a href="#omp_005finit_005fnest_005flock" accesskey="p" rel="prev">omp_init_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fset_005fnest_005flock-_002d_002d-Wait-for-and-set-nested-lock"></a>
<h3 class="section">2.27 <code>omp_set_nest_lock</code> &ndash; Wait for and set nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a nested lock, the lock variable must be initialized by 
<code>omp_init_nest_lock</code>. The calling thread is blocked until the lock 
is available. If the lock is already held by the current thread, the 
nesting count for the lock is incremented.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_set_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_set_nest_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005fnest_005flock">omp_init_nest_lock</a>, <a href="#omp_005funset_005fnest_005flock">omp_unset_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.3.
</p></dd>
</dl>



<hr>
<a name="omp_005ftest_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005funset_005fnest_005flock" accesskey="n" rel="next">omp_unset_nest_lock</a>, Previous: <a href="#omp_005fset_005fnest_005flock" accesskey="p" rel="prev">omp_set_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005ftest_005fnest_005flock-_002d_002d-Test-and-set-nested-lock-if-available"></a>
<h3 class="section">2.28 <code>omp_test_nest_lock</code> &ndash; Test and set nested lock if available</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Before setting a nested lock, the lock variable must be initialized by 
<code>omp_init_nest_lock</code>. Contrary to <code>omp_set_nest_lock</code>, 
<code>omp_test_nest_lock</code> does not block if the lock is not available. 
If the lock is already held by the current thread, the new nesting count 
is returned. Otherwise, the return value equals zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>int omp_test_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>logical function omp_test_nest_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: lock</code></td></tr>
</table>


</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>, <a href="#omp_005fset_005flock">omp_set_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.5.
</p></dd>
</dl>



<hr>
<a name="omp_005funset_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fdestroy_005fnest_005flock" accesskey="n" rel="next">omp_destroy_nest_lock</a>, Previous: <a href="#omp_005ftest_005fnest_005flock" accesskey="p" rel="prev">omp_test_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005funset_005fnest_005flock-_002d_002d-Unset-nested-lock"></a>
<h3 class="section">2.29 <code>omp_unset_nest_lock</code> &ndash; Unset nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>A nested lock about to be unset must have been locked by <code>omp_set_nested_lock</code>
or <code>omp_test_nested_lock</code> before. In addition, the lock must be held by the 
thread calling <code>omp_unset_nested_lock</code>. If the nesting count drops to zero, the 
lock becomes unlocked. If one ore more threads attempted to set the lock before, 
one of them is chosen to, again, set the lock to itself.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_unset_nest_lock(omp_nest_lock_t *lock);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_unset_nest_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnest_005flock">omp_set_nest_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.4.
</p></dd>
</dl>



<hr>
<a name="omp_005fdestroy_005fnest_005flock"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fwtick" accesskey="n" rel="next">omp_get_wtick</a>, Previous: <a href="#omp_005funset_005fnest_005flock" accesskey="p" rel="prev">omp_unset_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fdestroy_005fnest_005flock-_002d_002d-Destroy-nested-lock"></a>
<h3 class="section">2.30 <code>omp_destroy_nest_lock</code> &ndash; Destroy nested lock</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Destroy a nested lock. In order to be destroyed, a nested lock must be 
in the unlocked state and its nesting count must equal zero.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>void omp_destroy_nest_lock(omp_nest_lock_t *);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>subroutine omp_destroy_nest_lock(lock)</code></td></tr>
<tr><td width="20%"></td><td width="80%"><code>integer(omp_nest_lock_kind), intent(inout) :: lock</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005finit_005flock">omp_init_lock</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.3.2.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fwtick"></a>
<div class="header">
<p>
Next: <a href="#omp_005fget_005fwtime" accesskey="n" rel="next">omp_get_wtime</a>, Previous: <a href="#omp_005fdestroy_005fnest_005flock" accesskey="p" rel="prev">omp_destroy_nest_lock</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fwtick-_002d_002d-Get-timer-precision"></a>
<h3 class="section">2.31 <code>omp_get_wtick</code> &ndash; Get timer precision</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Gets the timer precision, i.e., the number of seconds between two 
successive clock ticks.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>double omp_get_wtick(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>double precision function omp_get_wtick()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fwtime">omp_get_wtime</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.4.2.
</p></dd>
</dl>



<hr>
<a name="omp_005fget_005fwtime"></a>
<div class="header">
<p>
Previous: <a href="#omp_005fget_005fwtick" accesskey="p" rel="prev">omp_get_wtick</a>, Up: <a href="#Runtime-Library-Routines" accesskey="u" rel="up">Runtime Library Routines</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="omp_005fget_005fwtime-_002d_002d-Elapsed-wall-clock-time"></a>
<h3 class="section">2.32 <code>omp_get_wtime</code> &ndash; Elapsed wall clock time</h3>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Elapsed wall clock time in seconds. The time is measured per thread, no 
guarantee can be made that two distinct threads measure the same time.
Time is measured from some &quot;time in the past&quot;, which is an arbitrary time
guaranteed not to change during the execution of the program.
</p>
</dd>
<dt><em>C/C++</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Prototype</em>:</td><td width="80%"><code>double omp_get_wtime(void);</code></td></tr>
</table>

</dd>
<dt><em>Fortran</em>:</dt>
<dd><table>
<tr><td width="20%"><em>Interface</em>:</td><td width="80%"><code>double precision function omp_get_wtime()</code></td></tr>
</table>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fget_005fwtick">omp_get_wtick</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 3.4.1.
</p></dd>
</dl>




<hr>
<a name="Environment-Variables"></a>
<div class="header">
<p>
Next: <a href="#The-libgomp-ABI" accesskey="n" rel="next">The libgomp ABI</a>, Previous: <a href="#Runtime-Library-Routines" accesskey="p" rel="prev">Runtime Library Routines</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Environment-Variables-1"></a>
<h2 class="chapter">3 Environment Variables</h2>

<p>The variables <code>OMP_DYNAMIC</code>, <code>OMP_MAX_ACTIVE_LEVELS</code>,
<code>OMP_NESTED</code>, <code>OMP_NUM_THREADS</code>, <code>OMP_SCHEDULE</code>,
<code>OMP_STACKSIZE</code>,<code>OMP_THREAD_LIMIT</code> and <code>OMP_WAIT_POLICY</code>
are defined by section 4 of the OpenMP specifications in version 3.1,
while <code>GOMP_CPU_AFFINITY</code> and <code>GOMP_STACKSIZE</code> are GNU 
extensions.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fDYNAMIC" accesskey="1">OMP_DYNAMIC</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Dynamic adjustment of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="2">OMP_MAX_ACTIVE_LEVELS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fNESTED" accesskey="3">OMP_NESTED</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fNUM_005fTHREADS" accesskey="4">OMP_NUM_THREADS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies the number of threads to use
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fSTACKSIZE" accesskey="5">OMP_STACKSIZE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fSCHEDULE" accesskey="6">OMP_SCHEDULE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How threads are scheduled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fTHREAD_005fLIMIT" accesskey="7">OMP_THREAD_LIMIT</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fWAIT_005fPOLICY" accesskey="8">OMP_WAIT_POLICY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How waiting threads are handled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OMP_005fPROC_005fBIND" accesskey="9">OMP_PROC_BIND</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether theads may be moved between CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Bind threads to specific CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
</table>


<hr>
<a name="OMP_005fDYNAMIC"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="n" rel="next">OMP_MAX_ACTIVE_LEVELS</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fDYNAMIC-_002d_002d-Dynamic-adjustment-of-threads"></a>
<h3 class="section">3.1 <code>OMP_DYNAMIC</code> &ndash; Dynamic adjustment of threads</h3>
<a name="index-Environment-Variable"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable the dynamic adjustment of the number of threads 
within a team. The value of this environment variable shall be 
<code>TRUE</code> or <code>FALSE</code>. If undefined, dynamic adjustment is
disabled by default.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fdynamic">omp_set_dynamic</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 4.3
</p></dd>
</dl>



<hr>
<a name="OMP_005fMAX_005fACTIVE_005fLEVELS"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fNESTED" accesskey="n" rel="next">OMP_NESTED</a>, Previous: <a href="#OMP_005fDYNAMIC" accesskey="p" rel="prev">OMP_DYNAMIC</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fMAX_005fACTIVE_005fLEVELS-_002d_002d-Set-the-maximum-number-of-nested-parallel-regions"></a>
<h3 class="section">3.2 <code>OMP_MAX_ACTIVE_LEVELS</code> &ndash; Set the maximum number of nested parallel regions</h3>
<a name="index-Environment-Variable-1"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the initial value for the maximum number of nested parallel
regions. The value of this variable shall be a positive integer.
If undefined, the number of active levels is unlimited.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fmax_005factive_005flevels">omp_set_max_active_levels</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 4.8
</p></dd>
</dl>



<hr>
<a name="OMP_005fNESTED"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fNUM_005fTHREADS" accesskey="n" rel="next">OMP_NUM_THREADS</a>, Previous: <a href="#OMP_005fMAX_005fACTIVE_005fLEVELS" accesskey="p" rel="prev">OMP_MAX_ACTIVE_LEVELS</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fNESTED-_002d_002d-Nested-parallel-regions"></a>
<h3 class="section">3.3 <code>OMP_NESTED</code> &ndash; Nested parallel regions</h3>
<a name="index-Environment-Variable-2"></a>
<a name="index-Implementation-specific-setting"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Enable or disable nested parallel regions, i.e., whether team members
are allowed to create new teams. The value of this environment variable 
shall be <code>TRUE</code> or <code>FALSE</code>. If undefined, nested parallel 
regions are disabled by default.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnested">omp_set_nested</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 4.5
</p></dd>
</dl>



<hr>
<a name="OMP_005fNUM_005fTHREADS"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fSCHEDULE" accesskey="n" rel="next">OMP_SCHEDULE</a>, Previous: <a href="#OMP_005fNESTED" accesskey="p" rel="prev">OMP_NESTED</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fNUM_005fTHREADS-_002d_002d-Specifies-the-number-of-threads-to-use"></a>
<h3 class="section">3.4 <code>OMP_NUM_THREADS</code> &ndash; Specifies the number of threads to use</h3>
<a name="index-Environment-Variable-3"></a>
<a name="index-Implementation-specific-setting-1"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the default number of threads to use in parallel regions. The 
value of this variable shall be a comma-separated list of positive integers;
the value specified the number of threads to use for the corresponding nested
level. If undefined one thread per CPU is used.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fnum_005fthreads">omp_set_num_threads</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 4.2
</p></dd>
</dl>



<hr>
<a name="OMP_005fSCHEDULE"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fSTACKSIZE" accesskey="n" rel="next">OMP_STACKSIZE</a>, Previous: <a href="#OMP_005fNUM_005fTHREADS" accesskey="p" rel="prev">OMP_NUM_THREADS</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fSCHEDULE-_002d_002d-How-threads-are-scheduled"></a>
<h3 class="section">3.5 <code>OMP_SCHEDULE</code> &ndash; How threads are scheduled</h3>
<a name="index-Environment-Variable-4"></a>
<a name="index-Implementation-specific-setting-2"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Allows to specify <code>schedule type</code> and <code>chunk size</code>. 
The value of the variable shall have the form: <code>type[,chunk]</code> where
<code>type</code> is one of <code>static</code>, <code>dynamic</code>, <code>guided</code> or <code>auto</code>
The optional <code>chunk</code> size shall be a positive integer. If undefined,
dynamic scheduling and a chunk size of 1 is used.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#omp_005fset_005fschedule">omp_set_schedule</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, sections 2.5.1 and 4.1
</p></dd>
</dl>



<hr>
<a name="OMP_005fSTACKSIZE"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fTHREAD_005fLIMIT" accesskey="n" rel="next">OMP_THREAD_LIMIT</a>, Previous: <a href="#OMP_005fSCHEDULE" accesskey="p" rel="prev">OMP_SCHEDULE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size"></a>
<h3 class="section">3.6 <code>OMP_STACKSIZE</code> &ndash; Set default thread stack size</h3>
<a name="index-Environment-Variable-5"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set the default thread stack size in kilobytes, unless the number
is suffixed by <code>B</code>, <code>K</code>, <code>M</code> or <code>G</code>, in which
case the size is, respectively, in bytes, kilobytes, megabytes
or gigabytes. This is different from <code>pthread_attr_setstacksize</code>
which gets the number of bytes as an argument. If the stack size cannot
be set due to system constraints, an error is reported and the initial
stack size is left unchanged. If undefined, the stack size is system
dependent.
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, sections 4.6
</p></dd>
</dl>



<hr>
<a name="OMP_005fTHREAD_005fLIMIT"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fWAIT_005fPOLICY" accesskey="n" rel="next">OMP_WAIT_POLICY</a>, Previous: <a href="#OMP_005fSTACKSIZE" accesskey="p" rel="prev">OMP_STACKSIZE</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fTHREAD_005fLIMIT-_002d_002d-Set-the-maximum-number-of-threads"></a>
<h3 class="section">3.7 <code>OMP_THREAD_LIMIT</code> &ndash; Set the maximum number of threads</h3>
<a name="index-Environment-Variable-6"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies the number of threads to use for the whole program. The
value of this variable shall be a positive integer. If undefined,
the number of threads is not limited.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a>
<a href="#omp_005fget_005fthread_005flimit">omp_get_thread_limit</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, section 4.9
</p></dd>
</dl>



<hr>
<a name="OMP_005fWAIT_005fPOLICY"></a>
<div class="header">
<p>
Next: <a href="#OMP_005fPROC_005fBIND" accesskey="n" rel="next">OMP_PROC_BIND</a>, Previous: <a href="#OMP_005fTHREAD_005fLIMIT" accesskey="p" rel="prev">OMP_THREAD_LIMIT</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fWAIT_005fPOLICY-_002d_002d-How-waiting-threads-are-handled"></a>
<h3 class="section">3.8 <code>OMP_WAIT_POLICY</code> &ndash; How waiting threads are handled</h3>
<a name="index-Environment-Variable-7"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies whether waiting threads should be active or passive. If
the value is <code>PASSIVE</code>, waiting threads should not consume CPU
power while waiting; while the value is <code>ACTIVE</code> specifies that
they should.
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, sections 4.7
</p></dd>
</dl>



<hr>
<a name="OMP_005fPROC_005fBIND"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fCPU_005fAFFINITY" accesskey="n" rel="next">GOMP_CPU_AFFINITY</a>, Previous: <a href="#OMP_005fWAIT_005fPOLICY" accesskey="p" rel="prev">OMP_WAIT_POLICY</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OMP_005fPROC_005fBIND-_002d_002d-Whether-theads-may-be-moved-between-CPUs"></a>
<h3 class="section">3.9 <code>OMP_PROC_BIND</code> &ndash; Whether theads may be moved between CPUs</h3>
<a name="index-Environment-Variable-8"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Specifies whether threads may be moved between processors. If set to
<code>true</code>, OpenMP theads should not be moved, if set to <code>false</code>
they may be moved.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://www.openmp.org/">OpenMP specifications v3.1</a>, sections 4.4
</p></dd>
</dl>



<hr>
<a name="GOMP_005fCPU_005fAFFINITY"></a>
<div class="header">
<p>
Next: <a href="#GOMP_005fSTACKSIZE" accesskey="n" rel="next">GOMP_STACKSIZE</a>, Previous: <a href="#OMP_005fPROC_005fBIND" accesskey="p" rel="prev">OMP_PROC_BIND</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fCPU_005fAFFINITY-_002d_002d-Bind-threads-to-specific-CPUs"></a>
<h3 class="section">3.10 <code>GOMP_CPU_AFFINITY</code> &ndash; Bind threads to specific CPUs</h3>
<a name="index-Environment-Variable-9"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Binds threads to specific CPUs. The variable should contain a space-separated
or comma-separated list of CPUs. This list may contain different kinds of 
entries: either single CPU numbers in any order, a range of CPUs (M-N) 
or a range with some stride (M-N:S).  CPU numbers are zero based. For example,
<code>GOMP_CPU_AFFINITY=&quot;0 3 1-2 4-15:2&quot;</code> will bind the initial thread
to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to 
CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8, 10, 12,
and 14 respectively and then start assigning back from the beginning of
the list.  <code>GOMP_CPU_AFFINITY=0</code> binds all threads to CPU 0.
</p>
<p>There is no GNU OpenMP library routine to determine whether a CPU affinity 
specification is in effect. As a workaround, language-specific library 
functions, e.g., <code>getenv</code> in C or <code>GET_ENVIRONMENT_VARIABLE</code> in 
Fortran, may be used to query the setting of the <code>GOMP_CPU_AFFINITY</code> 
environment variable. A defined CPU affinity on startup cannot be changed 
or disabled during the runtime of the application.
</p>
<p>If this environment variable is omitted, the host system will handle the 
assignment of threads to CPUs. 
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a>
</p></dd>
</dl>



<hr>
<a name="GOMP_005fSTACKSIZE"></a>
<div class="header">
<p>
Previous: <a href="#GOMP_005fCPU_005fAFFINITY" accesskey="p" rel="prev">GOMP_CPU_AFFINITY</a>, Up: <a href="#Environment-Variables" accesskey="u" rel="up">Environment Variables</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GOMP_005fSTACKSIZE-_002d_002d-Set-default-thread-stack-size"></a>
<h3 class="section">3.11 <code>GOMP_STACKSIZE</code> &ndash; Set default thread stack size</h3>
<a name="index-Environment-Variable-10"></a>
<a name="index-Implementation-specific-setting-3"></a>
<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p>Set the default thread stack size in kilobytes. This is different from
<code>pthread_attr_setstacksize</code> which gets the number of bytes as an 
argument. If the stack size cannot be set due to system constraints, an 
error is reported and the initial stack size is left unchanged. If undefined,
the stack size is system dependent.
</p>
</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="#OMP_005fSTACKSIZE">OMP_STACKSIZE</a>
</p>
</dd>
<dt><em>Reference</em>:</dt>
<dd><p><a href="http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00493.html">GCC Patches Mailinglist</a>, 
<a href="http://gcc.gnu.org/ml/gcc-patches/2006-06/msg00496.html">GCC Patches Mailinglist</a>
</p></dd>
</dl>




<hr>
<a name="The-libgomp-ABI"></a>
<div class="header">
<p>
Next: <a href="#Reporting-Bugs" accesskey="n" rel="next">Reporting Bugs</a>, Previous: <a href="#Environment-Variables" accesskey="p" rel="prev">Environment Variables</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-libgomp-ABI-1"></a>
<h2 class="chapter">4 The libgomp ABI</h2>

<p>The following sections present notes on the external ABI as 
presented by libgomp.  Only maintainers should need them.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Implementing-MASTER-construct" accesskey="1">Implementing MASTER construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-CRITICAL-construct" accesskey="2">Implementing CRITICAL construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-ATOMIC-construct" accesskey="3">Implementing ATOMIC construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FLUSH-construct" accesskey="4">Implementing FLUSH construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-BARRIER-construct" accesskey="5">Implementing BARRIER construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-THREADPRIVATE-construct" accesskey="6">Implementing THREADPRIVATE construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-PRIVATE-clause" accesskey="7">Implementing PRIVATE clause</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="8">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-REDUCTION-clause" accesskey="9">Implementing REDUCTION clause</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-PARALLEL-construct">Implementing PARALLEL construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-FOR-construct">Implementing FOR construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-ORDERED-construct">Implementing ORDERED construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-SECTIONS-construct">Implementing SECTIONS construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Implementing-SINGLE-construct">Implementing SINGLE construct</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>


<hr>
<a name="Implementing-MASTER-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-CRITICAL-construct" accesskey="n" rel="next">Implementing CRITICAL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-MASTER-construct-1"></a>
<h3 class="section">4.1 Implementing MASTER construct</h3>

<div class="smallexample">
<pre class="smallexample">if (omp_get_thread_num () == 0)
  block
</pre></div>

<p>Alternately, we generate two copies of the parallel subfunction
and only include this in the version run by the master thread.
Surely this is not worthwhile though...
</p>


<hr>
<a name="Implementing-CRITICAL-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-ATOMIC-construct" accesskey="n" rel="next">Implementing ATOMIC construct</a>, Previous: <a href="#Implementing-MASTER-construct" accesskey="p" rel="prev">Implementing MASTER construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-CRITICAL-construct-1"></a>
<h3 class="section">4.2 Implementing CRITICAL construct</h3>

<p>Without a specified name,
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_critical_start (void);
  void GOMP_critical_end (void);
</pre></div>

<p>so that we don&rsquo;t get COPY relocations from libgomp to the main
application.
</p>
<p>With a specified name, use omp_set_lock and omp_unset_lock with
name being transformed into a variable declared like
</p>
<div class="smallexample">
<pre class="smallexample">  omp_lock_t gomp_critical_user_&lt;name&gt; __attribute__((common))
</pre></div>

<p>Ideally the ABI would specify that all zero is a valid unlocked
state, and so we wouldn&rsquo;t need to initialize this at
startup.
</p>


<hr>
<a name="Implementing-ATOMIC-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FLUSH-construct" accesskey="n" rel="next">Implementing FLUSH construct</a>, Previous: <a href="#Implementing-CRITICAL-construct" accesskey="p" rel="prev">Implementing CRITICAL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-ATOMIC-construct-1"></a>
<h3 class="section">4.3 Implementing ATOMIC construct</h3>

<p>The target should implement the <code>__sync</code> builtins.
</p>
<p>Failing that we could add
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_atomic_enter (void)
  void GOMP_atomic_exit (void)
</pre></div>

<p>which reuses the regular lock code, but with yet another lock
object private to the library.
</p>


<hr>
<a name="Implementing-FLUSH-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-BARRIER-construct" accesskey="n" rel="next">Implementing BARRIER construct</a>, Previous: <a href="#Implementing-ATOMIC-construct" accesskey="p" rel="prev">Implementing ATOMIC construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FLUSH-construct-1"></a>
<h3 class="section">4.4 Implementing FLUSH construct</h3>

<p>Expands to the <code>__sync_synchronize</code> builtin.
</p>


<hr>
<a name="Implementing-BARRIER-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-THREADPRIVATE-construct" accesskey="n" rel="next">Implementing THREADPRIVATE construct</a>, Previous: <a href="#Implementing-FLUSH-construct" accesskey="p" rel="prev">Implementing FLUSH construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-BARRIER-construct-1"></a>
<h3 class="section">4.5 Implementing BARRIER construct</h3>

<div class="smallexample">
<pre class="smallexample">  void GOMP_barrier (void)
</pre></div>


<hr>
<a name="Implementing-THREADPRIVATE-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-PRIVATE-clause" accesskey="n" rel="next">Implementing PRIVATE clause</a>, Previous: <a href="#Implementing-BARRIER-construct" accesskey="p" rel="prev">Implementing BARRIER construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-THREADPRIVATE-construct-1"></a>
<h3 class="section">4.6 Implementing THREADPRIVATE construct</h3>

<p>In _most_ cases we can map this directly to <code>__thread</code>.  Except
that OMP allows constructors for C++ objects.  We can either
refuse to support this (how often is it used?) or we can 
implement something akin to .ctors.
</p>
<p>Even more ideally, this ctor feature is handled by extensions
to the main pthreads library.  Failing that, we can have a set
of entry points to register ctor functions to be called.
</p>


<hr>
<a name="Implementing-PRIVATE-clause"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="n" rel="next">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>, Previous: <a href="#Implementing-THREADPRIVATE-construct" accesskey="p" rel="prev">Implementing THREADPRIVATE construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-PRIVATE-clause-1"></a>
<h3 class="section">4.7 Implementing PRIVATE clause</h3>

<p>In association with a PARALLEL, or within the lexical extent
of a PARALLEL block, the variable becomes a local variable in
the parallel subfunction.
</p>
<p>In association with FOR or SECTIONS blocks, create a new
automatic variable within the current function.  This preserves
the semantic of new variable creation.
</p>


<hr>
<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses"></a>
<div class="header">
<p>
Next: <a href="#Implementing-REDUCTION-clause" accesskey="n" rel="next">Implementing REDUCTION clause</a>, Previous: <a href="#Implementing-PRIVATE-clause" accesskey="p" rel="prev">Implementing PRIVATE clause</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1"></a>
<h3 class="section">4.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</h3>

<p>This seems simple enough for PARALLEL blocks.  Create a private 
struct for communicating between the parent and subfunction.
In the parent, copy in values for scalar and &quot;small&quot; structs;
copy in addresses for others TREE_ADDRESSABLE types.  In the 
subfunction, copy the value into the local variable.
</p>
<p>It is not clear what to do with bare FOR or SECTION blocks.
The only thing I can figure is that we do something like:
</p>
<div class="smallexample">
<pre class="smallexample">#pragma omp for firstprivate(x) lastprivate(y)
for (int i = 0; i &lt; n; ++i)
  body;
</pre></div>

<p>which becomes
</p>
<div class="smallexample">
<pre class="smallexample">{
  int x = x, y;

  // for stuff

  if (i == n)
    y = y;
}
</pre></div>

<p>where the &quot;x=x&quot; and &quot;y=y&quot; assignments actually have different
uids for the two variables, i.e. not something you could write
directly in C.  Presumably this only makes sense if the &quot;outer&quot;
x and y are global variables.
</p>
<p>COPYPRIVATE would work the same way, except the structure 
broadcast would have to happen via SINGLE machinery instead.
</p>


<hr>
<a name="Implementing-REDUCTION-clause"></a>
<div class="header">
<p>
Next: <a href="#Implementing-PARALLEL-construct" accesskey="n" rel="next">Implementing PARALLEL construct</a>, Previous: <a href="#Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses" accesskey="p" rel="prev">Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-REDUCTION-clause-1"></a>
<h3 class="section">4.9 Implementing REDUCTION clause</h3>

<p>The private struct mentioned in the previous section should have 
a pointer to an array of the type of the variable, indexed by the 
thread&rsquo;s <var>team_id</var>.  The thread stores its final value into the 
array, and after the barrier, the master thread iterates over the
array to collect the values.
</p>

<hr>
<a name="Implementing-PARALLEL-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-FOR-construct" accesskey="n" rel="next">Implementing FOR construct</a>, Previous: <a href="#Implementing-REDUCTION-clause" accesskey="p" rel="prev">Implementing REDUCTION clause</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-PARALLEL-construct-1"></a>
<h3 class="section">4.10 Implementing PARALLEL construct</h3>

<div class="smallexample">
<pre class="smallexample">  #pragma omp parallel
  {
    body;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  void subfunction (void *data)
  {
    use data;
    body;
  }

  setup data;
  GOMP_parallel_start (subfunction, &amp;data, num_threads);
  subfunction (&amp;data);
  GOMP_parallel_end ();
</pre></div>

<div class="smallexample">
<pre class="smallexample">  void GOMP_parallel_start (void (*fn)(void *), void *data, unsigned num_threads)
</pre></div>

<p>The <var>FN</var> argument is the subfunction to be run in parallel.
</p>
<p>The <var>DATA</var> argument is a pointer to a structure used to 
communicate data in and out of the subfunction, as discussed
above with respect to FIRSTPRIVATE et al.
</p>
<p>The <var>NUM_THREADS</var> argument is 1 if an IF clause is present
and false, or the value of the NUM_THREADS clause, if
present, or 0.
</p>
<p>The function needs to create the appropriate number of
threads and/or launch them from the dock.  It needs to
create the team structure and assign team ids.
</p>
<div class="smallexample">
<pre class="smallexample">  void GOMP_parallel_end (void)
</pre></div>

<p>Tears down the team and returns us to the previous <code>omp_in_parallel()</code> state.
</p>


<hr>
<a name="Implementing-FOR-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-ORDERED-construct" accesskey="n" rel="next">Implementing ORDERED construct</a>, Previous: <a href="#Implementing-PARALLEL-construct" accesskey="p" rel="prev">Implementing PARALLEL construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-FOR-construct-1"></a>
<h3 class="section">4.11 Implementing FOR construct</h3>

<div class="smallexample">
<pre class="smallexample">  #pragma omp parallel for
  for (i = lb; i &lt;= ub; i++)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  void subfunction (void *data)
  {
    long _s0, _e0;
    while (GOMP_loop_static_next (&amp;_s0, &amp;_e0))
    {
      long _e1 = _e0, i;
      for (i = _s0; i &lt; _e1; i++)
        body;
    }
    GOMP_loop_end_nowait ();
  }

  GOMP_parallel_loop_static (subfunction, NULL, 0, lb, ub+1, 1, 0);
  subfunction (NULL);
  GOMP_parallel_end ();
</pre></div>

<div class="smallexample">
<pre class="smallexample">  #pragma omp for schedule(runtime)
  for (i = 0; i &lt; n; i++)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  {
    long i, _s0, _e0;
    if (GOMP_loop_runtime_start (0, n, 1, &amp;_s0, &amp;_e0))
      do {
        long _e1 = _e0;
        for (i = _s0, i &lt; _e0; i++)
          body;
      } while (GOMP_loop_runtime_next (&amp;_s0, _&amp;e0));
    GOMP_loop_end ();
  }
</pre></div>

<p>Note that while it looks like there is trickiness to propagating
a non-constant STEP, there isn&rsquo;t really.  We&rsquo;re explicitly allowed
to evaluate it as many times as we want, and any variables involved
should automatically be handled as PRIVATE or SHARED like any other
variables.  So the expression should remain evaluable in the 
subfunction.  We can also pull it into a local variable if we like,
but since its supposed to remain unchanged, we can also not if we like.
</p>
<p>If we have SCHEDULE(STATIC), and no ORDERED, then we ought to be
able to get away with no work-sharing context at all, since we can
simply perform the arithmetic directly in each thread to divide up
the iterations.  Which would mean that we wouldn&rsquo;t need to call any
of these routines.
</p>
<p>There are separate routines for handling loops with an ORDERED
clause.  Bookkeeping for that is non-trivial...
</p>


<hr>
<a name="Implementing-ORDERED-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-SECTIONS-construct" accesskey="n" rel="next">Implementing SECTIONS construct</a>, Previous: <a href="#Implementing-FOR-construct" accesskey="p" rel="prev">Implementing FOR construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-ORDERED-construct-1"></a>
<h3 class="section">4.12 Implementing ORDERED construct</h3>

<div class="smallexample">
<pre class="smallexample">  void GOMP_ordered_start (void)
  void GOMP_ordered_end (void)
</pre></div>



<hr>
<a name="Implementing-SECTIONS-construct"></a>
<div class="header">
<p>
Next: <a href="#Implementing-SINGLE-construct" accesskey="n" rel="next">Implementing SINGLE construct</a>, Previous: <a href="#Implementing-ORDERED-construct" accesskey="p" rel="prev">Implementing ORDERED construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-SECTIONS-construct-1"></a>
<h3 class="section">4.13 Implementing SECTIONS construct</h3>

<p>A block as 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp sections
  {
    #pragma omp section
    stmt1;
    #pragma omp section
    stmt2;
    #pragma omp section
    stmt3;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  for (i = GOMP_sections_start (3); i != 0; i = GOMP_sections_next ())
    switch (i)
      {
      case 1:
        stmt1;
        break;
      case 2:
        stmt2;
        break;
      case 3:
        stmt3;
        break;
      }
  GOMP_barrier ();
</pre></div>


<hr>
<a name="Implementing-SINGLE-construct"></a>
<div class="header">
<p>
Previous: <a href="#Implementing-SECTIONS-construct" accesskey="p" rel="prev">Implementing SECTIONS construct</a>, Up: <a href="#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Implementing-SINGLE-construct-1"></a>
<h3 class="section">4.14 Implementing SINGLE construct</h3>

<p>A block like 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp single
  {
    body;
  }
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  if (GOMP_single_start ())
    body;
  GOMP_barrier ();
</pre></div>

<p>while 
</p>
<div class="smallexample">
<pre class="smallexample">  #pragma omp single copyprivate(x)
    body;
</pre></div>

<p>becomes
</p>
<div class="smallexample">
<pre class="smallexample">  datap = GOMP_single_copy_start ();
  if (datap == NULL)
    {
      body;
      data.x = x;
      GOMP_single_copy_end (&amp;data);
    }
  else
    x = datap-&gt;x;
  GOMP_barrier ();
</pre></div>




<hr>
<a name="Reporting-Bugs"></a>
<div class="header">
<p>
Next: <a href="#Copying" accesskey="n" rel="next">Copying</a>, Previous: <a href="#The-libgomp-ABI" accesskey="p" rel="prev">The libgomp ABI</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Reporting-Bugs-1"></a>
<h2 class="chapter">5 Reporting Bugs</h2>

<p>Bugs in the GNU OpenMP implementation should be reported via 
<a href="http://gcc.gnu.org/bugzilla/">bugzilla</a>.  For all cases, please add 
&quot;openmp&quot; to the keywords field in the bug report.
</p>



<hr>
<a name="Copying"></a>
<div class="header">
<p>
Next: <a href="#GNU-Free-Documentation-License" accesskey="n" rel="next">GNU Free Documentation License</a>, Previous: <a href="#Reporting-Bugs" accesskey="p" rel="prev">Reporting Bugs</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GNU-GENERAL-PUBLIC-LICENSE"></a>
<h2 class="unnumbered">GNU GENERAL PUBLIC LICENSE</h2>
<div align="center">Version 2, June 1991
</div>

<div class="display">
<pre class="display">Copyright &copy; 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<a name="Preamble"></a>
<h3 class="unnumberedsec">Preamble</h3>

<p>The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software&mdash;to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation&rsquo;s software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.
</p>
<p>When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
</p>
<p>To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
</p>
<p>For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.
</p>
<p>We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
</p>
<p>Also, for each author&rsquo;s protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors&rsquo; reputations.
</p>
<p>Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone&rsquo;s free use or not licensed at all.
</p>
<p>The precise terms and conditions for copying, distribution and
modification follow.
</p>
<div align="center">TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
</div>
<ol>
<li> This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The &ldquo;Program&rdquo;, below,
refers to any such program or work, and a &ldquo;work based on the Program&rdquo;
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language.  (Hereinafter, translation is included without limitation in
the term &ldquo;modification&rdquo;.)  Each licensee is addressed as &ldquo;you&rdquo;.

<p>Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
</p>
</li><li> You may copy and distribute verbatim copies of the Program&rsquo;s
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

<p>You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
</p>
</li><li> You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:

<ol>
<li> You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.

</li><li> You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.

</li><li> If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License.  (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
</li></ol>

<p>These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works.  But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
</p>
<p>Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
</p>
<p>In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
</p>
</li><li> You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:

<ol>
<li> Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,

</li><li> Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,

</li><li> Accompany it with the information you received as to the offer
to distribute corresponding source code.  (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
</li></ol>

<p>The source code for a work means the preferred form of the work for
making modifications to it.  For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable.  However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
</p>
<p>If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
</p>
</li><li> You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.

</li><li> You are not required to accept this License, since you have not
signed it.  However, nothing else grants you permission to modify or
distribute the Program or its derivative works.  These actions are
prohibited by law if you do not accept this License.  Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.

</li><li> Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions.  You may not impose any further
restrictions on the recipients&rsquo; exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.

</li><li> If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

<p>If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.
</p>
<p>It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices.  Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
</p>
<p>This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
</p>
</li><li> If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded.  In such case, this License incorporates
the limitation as if written in the body of this License.

</li><li> The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

<p>Each version is given a distinguishing version number.  If the Program
specifies a version number of this License which applies to it and &ldquo;any
later version&rdquo;, you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation.  If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.
</p>
</li><li> If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission.  For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this.  Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.

<div align="center">NO WARRANTY
</div>
</li><li> BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM &ldquo;AS IS&rdquo; WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.

</li><li> IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
</li></ol>

<div align="center">END OF TERMS AND CONDITIONS
</div>
<a name="Appendix_003a-How-to-Apply-These-Terms-to-Your-New-Programs"></a>
<h3 class="unnumberedsec">Appendix: How to Apply These Terms to Your New Programs</h3>

<p>If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
</p>
<p>To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the &ldquo;copyright&rdquo; line and a pointer to where the full notice is found.
</p>
<div class="smallexample">
<pre class="smallexample"><var>one line to give the program's name and a brief idea of what it does.</var>
Copyright (C) <var>year</var>  <var>name of author</var>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
</pre></div>

<p>Also add information on how to contact you by electronic and paper mail.
</p>
<p>If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
</p>
<div class="smallexample">
<pre class="smallexample">Gnomovision version 69, Copyright (C) <var>year</var> <var>name of author</var>
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
</pre></div>

<p>The hypothetical commands &lsquo;<samp>show w</samp>&rsquo; and &lsquo;<samp>show c</samp>&rsquo; should show
the appropriate parts of the General Public License.  Of course, the
commands you use may be called something other than &lsquo;<samp>show w</samp>&rsquo; and
&lsquo;<samp>show c</samp>&rsquo;; they could even be mouse-clicks or menu items&mdash;whatever
suits your program.
</p>
<p>You should also get your employer (if you work as a programmer) or your
school, if any, to sign a &ldquo;copyright disclaimer&rdquo; for the program, if
necessary.  Here is a sample; alter the names:
</p>
<div class="example">
<pre class="example">Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.

<var>signature of Ty Coon</var>, 1 April 1989
Ty Coon, President of Vice
</pre></div>

<p>This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.
</p>



<hr>
<a name="GNU-Free-Documentation-License"></a>
<div class="header">
<p>
Next: <a href="#Funding" accesskey="n" rel="next">Funding</a>, Previous: <a href="#Copying" accesskey="p" rel="prev">Copying</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GNU-Free-Documentation-License-1"></a>
<h2 class="unnumbered">GNU Free Documentation License</h2>

<a name="index-FDL_002c-GNU-Free-Documentation-License"></a>
<div align="center">Version 1.3, 3 November 2008
</div>
<div class="display">
<pre class="display">Copyright &copy; 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<ol>
<li> PREAMBLE

<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em>free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of &ldquo;copyleft&rdquo;, which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS

<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The &ldquo;Document&rdquo;, below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as &ldquo;you&rdquo;.  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A &ldquo;Modified Version&rdquo; of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A &ldquo;Secondary Section&rdquo; is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document&rsquo;s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The &ldquo;Invariant Sections&rdquo; are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The &ldquo;Cover Texts&rdquo; are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A &ldquo;Transparent&rdquo; copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not &ldquo;Transparent&rdquo; is called &ldquo;Opaque&rdquo;.
</p>
<p>Examples of suitable formats for Transparent copies include plain
<small>ASCII</small> without markup, Texinfo input format, LaTeX input
format, <acronym>SGML</acronym> or <acronym>XML</acronym> using a publicly available
<acronym>DTD</acronym>, and standard-conforming simple <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> designed for human modification.  Examples
of transparent image formats include <acronym>PNG</acronym>, <acronym>XCF</acronym> and
<acronym>JPG</acronym>.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <acronym>SGML</acronym> or
<acronym>XML</acronym> for which the <acronym>DTD</acronym> and/or processing tools are
not generally available, and the machine-generated <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> produced by some word processors for
output purposes only.
</p>
<p>The &ldquo;Title Page&rdquo; means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, &ldquo;Title Page&rdquo; means
the text near the most prominent appearance of the work&rsquo;s title,
preceding the beginning of the body of the text.
</p>
<p>The &ldquo;publisher&rdquo; means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section &ldquo;Entitled XYZ&rdquo; means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, &ldquo;Endorsements&rdquo;, or &ldquo;History&rdquo;.)  To &ldquo;Preserve the Title&rdquo;
of such a section when you modify the Document means that it remains a
section &ldquo;Entitled XYZ&rdquo; according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING

<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY

<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document&rsquo;s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS

<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</p>
<ol>
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.

</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.

</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.

</li><li> Preserve all the copyright notices of the Document.

</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.

</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document&rsquo;s license notice.

</li><li> Include an unaltered copy of this License.

</li><li> Preserve the section Entitled &ldquo;History&rdquo;, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled &ldquo;History&rdquo; in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.

</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the &ldquo;History&rdquo; section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.

</li><li> For any section Entitled &ldquo;Acknowledgements&rdquo; or &ldquo;Dedications&rdquo;, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.

</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.

</li><li> Delete any section Entitled &ldquo;Endorsements&rdquo;.  Such a section
may not be included in the Modified Version.

</li><li> Do not retitle any existing section to be Entitled &ldquo;Endorsements&rdquo; or
to conflict in title with any Invariant Section.

</li><li> Preserve any Warranty Disclaimers.
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</li><li> COMBINING DOCUMENTS

<p>You may combine the Document with other documents released under this
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<p>The combined work need only contain one copy of this License, and
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</li><li> COLLECTIONS OF DOCUMENTS

<p>You may make a collection consisting of the Document and other documents
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</li><li> AGGREGATION WITH INDEPENDENT WORKS

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</p>
<p>If the Cover Text requirement of section 3 is applicable to these
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</li><li> TRANSLATION

<p>Translation is considered a kind of modification, so you may
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<p>If a section in the Document is Entitled &ldquo;Acknowledgements&rdquo;,
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</li><li> TERMINATION

<p>You may not copy, modify, sublicense, or distribute the Document
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<p>However, if you cease all violation of this License, then your license
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<p>Moreover, your license from a particular copyright holder is
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<p>Termination of your rights under this section does not terminate the
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</li><li> FUTURE REVISIONS OF THIS LICENSE

<p>The Free Software Foundation may publish new, revised versions
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<p>Each version of the License is given a distinguishing version number.
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<p>&ldquo;Massive Multiauthor Collaboration Site&rdquo; (or &ldquo;MMC Site&rdquo;) means any
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<p>&ldquo;CC-BY-SA&rdquo; means the Creative Commons Attribution-Share Alike 3.0
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</p>
<p>&ldquo;Incorporate&rdquo; means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is &ldquo;eligible for relicensing&rdquo; if it is licensed under this
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<p>The operator of an MMC Site may republish an MMC contained in the site
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</p>
</li></ol>

<a name="ADDENDUM_003a-How-to-use-this-License-for-your-documents"></a>
<h3 class="unnumberedsec">ADDENDUM: How to use this License for your documents</h3>

<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="smallexample">
<pre class="smallexample">  Copyright (C)  <var>year</var>  <var>your name</var>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</pre></div>

<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the &ldquo;with...Texts.&rdquo; line with this:
</p>
<div class="smallexample">
<pre class="smallexample">    with the Invariant Sections being <var>list their titles</var>, with
    the Front-Cover Texts being <var>list</var>, and with the Back-Cover Texts
    being <var>list</var>.
</pre></div>

<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>





<hr>
<a name="Funding"></a>
<div class="header">
<p>
Next: <a href="#Index" accesskey="n" rel="next">Index</a>, Previous: <a href="#GNU-Free-Documentation-License" accesskey="p" rel="prev">GNU Free Documentation License</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Funding-Free-Software"></a>
<h2 class="unnumbered">Funding Free Software</h2>

<p>If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development.  The most effective approach known is to encourage
commercial redistributors to donate.
</p>
<p>Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers&mdash;the Free Software Foundation, and others.
</p>
<p>The way to convince distributors to do this is to demand it and expect
it from them.  So when you compare distributors, judge them partly by
how much they give to free software development.  Show distributors
they must compete to be the one who gives the most.
</p>
<p>To make this approach work, you must insist on numbers that you can
compare, such as, &ldquo;We will donate ten dollars to the Frobnitz project
for each disk sold.&rdquo;  Don&rsquo;t be satisfied with a vague promise, such as
&ldquo;A portion of the profits are donated,&rdquo; since it doesn&rsquo;t give a basis
for comparison.
</p>
<p>Even a precise fraction &ldquo;of the profits from this disk&rdquo; is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.
If the price you pay is $50, ten percent of the profit is probably
less than a dollar; it might be a few cents, or nothing at all.
</p>
<p>Some redistributors do development work themselves.  This is useful too;
but to keep everyone honest, you need to inquire how much they do, and
what kind.  Some kinds of development make much more long-term
difference than others.  For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much.  Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU Compiler Collection contribute more;
major new features or packages contribute the most.
</p>
<p>By establishing the idea that supporting further development is &ldquo;the
proper thing to do&rdquo; when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.
</p>
<div class="display">
<pre class="display">Copyright &copy; 1994 Free Software Foundation, Inc.
Verbatim copying and redistribution of this section is permitted
without royalty; alteration is not permitted.
</pre></div>


<hr>
<a name="Index"></a>
<div class="header">
<p>
Previous: <a href="#Funding" accesskey="p" rel="prev">Funding</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Index-1"></a>
<h2 class="unnumbered">Index</h2>

<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter" href="#Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter" href="#Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
</td></tr></table>
<table class="index-cp" border="0">
<tr><td></td><th align="left">Index Entry</th><td>&nbsp;</td><th align="left"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Index_cp_letter-E">E</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fDYNAMIC">OMP_DYNAMIC</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-1">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fMAX_005fACTIVE_005fLEVELS">OMP_MAX_ACTIVE_LEVELS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-2">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNESTED">OMP_NESTED</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-3">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-4">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-5">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSTACKSIZE">OMP_STACKSIZE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-6">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fTHREAD_005fLIMIT">OMP_THREAD_LIMIT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-7">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fWAIT_005fPOLICY">OMP_WAIT_POLICY</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-8">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fPROC_005fBIND">OMP_PROC_BIND</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-9">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fCPU_005fAFFINITY">GOMP_CPU_AFFINITY</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Environment-Variable-10">Environment Variable</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Index_cp_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-FDL_002c-GNU-Free-Documentation-License">FDL, GNU Free Documentation License</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Index_cp_letter-I">I</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNESTED">OMP_NESTED</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-1">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fNUM_005fTHREADS">OMP_NUM_THREADS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-2">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OMP_005fSCHEDULE">OMP_SCHEDULE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Implementation-specific-setting-3">Implementation specific setting</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GOMP_005fSTACKSIZE">GOMP_STACKSIZE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Introduction">Introduction</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Top">Top</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter" href="#Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter" href="#Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
</td></tr></table>

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