/usr/include/deal.II/lac/identity_matrix.h is in libdeal.ii-dev 8.1.0-6ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 | // ---------------------------------------------------------------------
// $Id: identity_matrix.h 30040 2013-07-18 17:06:48Z maier $
//
// Copyright (C) 2006 - 2013 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------
#ifndef __deal2__identity_matrix_h
#define __deal2__identity_matrix_h
#include <deal.II/base/config.h>
#include <deal.II/lac/exceptions.h>
DEAL_II_NAMESPACE_OPEN
/*! @addtogroup Matrix1
*@{
*/
/**
* Implementation of a simple class representing the identity matrix
* of a given size, i.e. a matrix with entries
* $A_{ij}=\delta_{ij}$. While it has the most important ingredients
* of a matrix, in particular that one can ask for its size and
* perform matrix-vector products with it, a matrix of this type is
* really only useful in two contexts: preconditioning and
* initializing other matrices.
*
* <h4>Initialization</h4>
*
* The main usefulness of this class lies in its ability to initialize
* other matrix, like this:
@code
FullMatrix<double> identity (IdentityMatrix(10));
@endcode
*
* This creates a $10\times 10$ matrix with ones on the diagonal and
* zeros everywhere else. Most matrix types, in particular FullMatrix
* and SparseMatrix, have conversion constructors and assignment
* operators for IdentityMatrix, and can therefore be filled rather
* easily with identity matrices.
*
*
* <h4>Preconditioning</h4>
*
* No preconditioning at all is equivalent to preconditioning with
* preconditioning with the identity matrix. deal.II has a specialized
* class for this purpose, PreconditionIdentity, than can be used in a
* context as shown in the documentation of that class. The present
* class can be used in much the same way, although without any
* additional benefit:
@code
SolverControl solver_control (1000, 1e-12);
SolverCG<> cg (solver_control);
cg.solve (system_matrix, solution, system_rhs,
IdentityMatrix(solution.size()));
@endcode
*
*
* @author Wolfgang Bangerth, 2006
*/
class IdentityMatrix
{
public:
/**
* Declate type for container size.
*/
typedef types::global_dof_index size_type;
/**
* Default constructor. Creates a
* zero-sized matrix that should
* be resized later on using the
* reinit() function.
*/
IdentityMatrix ();
/**
* Constructor. Creates a
* identity matrix of size #n.
*/
IdentityMatrix (const size_type n);
/**
* Resize the matrix to be of
* size #n by #n.
*/
void reinit (const size_type n);
/**
* Number of rows of this
* matrix. For the present
* matrix, the number of rows and
* columns are equal, of course.
*/
size_type m () const;
/**
* Number of columns of this
* matrix. For the present
* matrix, the number of rows and
* columns are equal, of course.
*/
size_type n () const;
/**
* Matrix-vector
* multiplication. For the
* present case, this of course
* amounts to simply copying the
* input vector to the output
* vector.
*/
template <class VECTOR1, class VECTOR2>
void vmult (VECTOR1 &out,
const VECTOR2 &in) const;
/**
* Matrix-vector multiplication
* with addition to the output
* vector. For the present case,
* this of course amounts to
* simply adding the input
* vector to the output vector.
*/
template <class VECTOR1, class VECTOR2>
void vmult_add (VECTOR1 &out,
const VECTOR2 &in) const;
/**
* Matrix-vector multiplication
* with the transpose matrix. For
* the present case, this of
* course amounts to simply
* copying the input vector to
* the output vector.
*/
template <class VECTOR1, class VECTOR2>
void Tvmult (VECTOR1 &out,
const VECTOR2 &in) const;
/**
* Matrix-vector multiplication
* with the transpose matrix,
* with addition to the output
* vector. For the present case,
* this of course amounts to
* simply adding the input vector
* to the output vector.
*/
template <class VECTOR1, class VECTOR2>
void Tvmult_add (VECTOR1 &out,
const VECTOR2 &in) const;
private:
/**
* Number of rows and columns of
* this matrix.
*/
size_type size;
};
// ------------------------- inline and template functions -------------
#ifndef DOXYGEN
inline
IdentityMatrix::IdentityMatrix ()
:
size (0)
{}
inline
IdentityMatrix::IdentityMatrix (const size_type n)
:
size (n)
{}
inline
void
IdentityMatrix::reinit (const size_type n)
{
size = n;
}
inline
IdentityMatrix::size_type
IdentityMatrix::m () const
{
return size;
}
inline
IdentityMatrix::size_type
IdentityMatrix::n () const
{
return size;
}
template <class VECTOR1, class VECTOR2>
inline
void
IdentityMatrix::vmult (VECTOR1 &out,
const VECTOR2 &in) const
{
Assert (out.size() == size, ExcDimensionMismatch (out.size(), size));
Assert (in.size() == size, ExcDimensionMismatch (in.size(), size));
out = in;
}
template <class VECTOR1, class VECTOR2>
inline
void
IdentityMatrix::vmult_add (VECTOR1 &out,
const VECTOR2 &in) const
{
Assert (out.size() == size, ExcDimensionMismatch (out.size(), size));
Assert (in.size() == size, ExcDimensionMismatch (in.size(), size));
out += in;
}
template <class VECTOR1, class VECTOR2>
inline
void
IdentityMatrix::Tvmult (VECTOR1 &out,
const VECTOR2 &in) const
{
Assert (out.size() == size, ExcDimensionMismatch (out.size(), size));
Assert (in.size() == size, ExcDimensionMismatch (in.size(), size));
out = in;
}
template <class VECTOR1, class VECTOR2>
inline
void
IdentityMatrix::Tvmult_add (VECTOR1 &out,
const VECTOR2 &in) const
{
Assert (out.size() == size, ExcDimensionMismatch (out.size(), size));
Assert (in.size() == size, ExcDimensionMismatch (in.size(), size));
out += in;
}
#endif
/**@}*/
DEAL_II_NAMESPACE_CLOSE
#endif
|