/usr/include/sofa/component/linearsolver/CGLinearSolver.h is in libsofa1-dev 1.0~beta4-10ubuntu2.
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* SOFA, Simulation Open-Framework Architecture, version 1.0 beta 4 *
* (c) 2006-2009 MGH, INRIA, USTL, UJF, CNRS *
* *
* This library is free software; you can 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. *
* *
* This library 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 Lesser General Public License *
* for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this library; if not, write to the Free Software Foundation, *
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
*******************************************************************************
* SOFA :: Modules *
* *
* Authors: The SOFA Team and external contributors (see Authors.txt) *
* *
* Contact information: contact@sofa-framework.org *
******************************************************************************/
#ifndef SOFA_COMPONENT_LINEARSOLVER_CGLINEARSOLVER_H
#define SOFA_COMPONENT_LINEARSOLVER_CGLINEARSOLVER_H
#include <sofa/core/componentmodel/behavior/LinearSolver.h>
#include <sofa/component/linearsolver/MatrixLinearSolver.h>
#include <sofa/simulation/common/MechanicalVisitor.h>
#include <sofa/helper/map.h>
#include <math.h>
namespace sofa
{
namespace component
{
namespace linearsolver
{
//#define DISPLAY_TIME
#ifdef DISPLAY_TIME
#include <sofa/helper/system/thread/CTime.h>
using sofa::helper::system::thread::CTime;
#endif
/// Linear system solver using the conjugate gradient iterative algorithm
template<class TMatrix, class TVector>
class SOFA_COMPONENT_LINEARSOLVER_API CGLinearSolver : public sofa::component::linearsolver::MatrixLinearSolver<TMatrix,TVector>, public virtual sofa::core::objectmodel::BaseObject
{
public:
typedef TMatrix Matrix;
typedef TVector Vector;
typedef sofa::component::linearsolver::MatrixLinearSolver<TMatrix,TVector> Inherit;
Data<unsigned> f_maxIter;
Data<double> f_tolerance;
Data<double> f_smallDenominatorThreshold;
Data<bool> f_verbose;
Data<std::map < std::string, sofa::helper::vector<double> > > f_graph;
#ifdef DISPLAY_TIME
double time1;
double time2;
double timeStamp;
#endif
CGLinearSolver()
: f_maxIter( initData(&f_maxIter,(unsigned)25,"iterations","maximum number of iterations of the Conjugate Gradient solution") )
, f_tolerance( initData(&f_tolerance,1e-5,"tolerance","desired precision of the Conjugate Gradient Solution (ratio of current residual norm over initial residual norm)") )
, f_smallDenominatorThreshold( initData(&f_smallDenominatorThreshold,1e-5,"threshold","minimum value of the denominator in the conjugate Gradient solution") )
, f_verbose( initData(&f_verbose,false,"verbose","Dump system state at each iteration") )
, f_graph( initData(&f_graph,"graph","Graph of residuals at each iteration") )
{
f_graph.setWidget("graph");
f_graph.setReadOnly(true);
#ifdef DISPLAY_TIME
timeStamp = 1.0 / (double)CTime::getRefTicksPerSec();
#endif
}
protected:
/// This method is separated from the rest to be able to use custom/optimized versions depending on the types of vectors.
/// It computes: p = p*beta + r
inline void cgstep_beta(Vector& p, Vector& r, double beta);
/// This method is separated from the rest to be able to use custom/optimized versions depending on the types of vectors.
/// It computes: x += p*alpha, r -= q*alpha
inline void cgstep_alpha(Vector& x, Vector& r, Vector& p, Vector& q, double alpha);
public:
/// Solve Mx=b
void solve (Matrix& M, Vector& x, Vector& b)
{
Vector& p = *this->createVector();
Vector& q = *this->createVector();
Vector& r = *this->createVector();
const bool printLog = f_printLog.getValue();
const bool verbose = f_verbose.getValue();
// -- solve the system using a conjugate gradient solution
double rho, rho_1=0, alpha, beta;
if( verbose )
serr<<"CGLinearSolver, b = "<< b <<sendl;
x.clear();
r = b; // initial residual
double normb2 = b.dot(b);
double normb = sqrt(normb2);
std::map < std::string, sofa::helper::vector<double> >& graph = *f_graph.beginEdit();
sofa::helper::vector<double>& graph_error = graph["Error"];
graph_error.clear();
sofa::helper::vector<double>& graph_den = graph["Denominator"];
graph_den.clear();
graph_error.push_back(1);
unsigned nb_iter;
const char* endcond = "iterations";
#ifdef DISPLAY_TIME
CTime * timer;
time1 = (double) timer->getTime();
#endif
for( nb_iter=1; nb_iter<=f_maxIter.getValue(); nb_iter++ )
{
#ifdef DUMP_VISITOR_INFO
std::ostringstream comment;
comment << "Iteration : " << nb_iter;
simulation::Visitor::printComment(comment.str());
#endif
// printWithElapsedTime( x, helper::system::thread::CTime::getTime()-time0,sout );
//z = r; // no precond
//rho = r.dot(z);
rho = (nb_iter==1) ? normb2 : r.dot(r);
if (nb_iter>1)
{
double normr = sqrt(rho); //sqrt(r.dot(r));
double err = normr/normb;
graph_error.push_back(err);
if (err <= f_tolerance.getValue())
{
endcond = "tolerance";
break;
}
}
if( nb_iter==1 )
p = r; //z;
else
{
beta = rho / rho_1;
//p = p*beta + r; //z;
cgstep_beta(p,r,beta);
}
if( verbose )
{
serr<<"p : "<<p<<sendl;
}
// matrix-vector product
q = M*p;
if( verbose )
{
serr<<"q = M p : "<<q<<sendl;
}
double den = p.dot(q);
graph_den.push_back(den);
if( fabs(den)<f_smallDenominatorThreshold.getValue() )
{
endcond = "threshold";
if( verbose )
{
serr<<"CGLinearSolver, den = "<<den<<", smallDenominatorThreshold = "<<f_smallDenominatorThreshold.getValue()<<sendl;
}
break;
}
alpha = rho/den;
//x.peq(p,alpha); // x = x + alpha p
//r.peq(q,-alpha); // r = r - alpha q
cgstep_alpha(x,r,p,q,alpha);
if( verbose ){
serr<<"den = "<<den<<", alpha = "<<alpha<<sendl;
serr<<"x : "<<x<<sendl;
serr<<"r : "<<r<<sendl;
}
rho_1 = rho;
}
#ifdef DISPLAY_TIME
time1 = (double)(((double) timer->getTime() - time1) * timeStamp / (nb_iter-1));
#endif
f_graph.endEdit();
// x is the solution of the system
if( printLog )
{
#ifdef DISPLAY_TIME
cerr<<"CGLinearSolver::solve, CG = "<<time1<<" bluid = "<<time2<<endl;
#endif
serr<<"CGLinearSolver::solve, nbiter = "<<nb_iter<<" stop because of "<<endcond<<sendl;
}
if( verbose )
{
serr<<"CGLinearSolver::solve, solution = "<<x<<sendl;
}
this->deleteVector(&p);
this->deleteVector(&q);
this->deleteVector(&r);
}
#ifdef DISPLAY_TIME
void setSystemMBKMatrix(double mFact, double bFact, double kFact) {
CTime * timer;
time2 = (double) timer->getTime();
Inherit::setSystemMBKMatrix(mFact,bFact,kFact);
time2 = ((double) timer->getTime() - time2) * timeStamp;
}
#endif
};
template<class TMatrix, class TVector>
inline void CGLinearSolver<TMatrix,TVector>::cgstep_beta(Vector& p, Vector& r, double beta)
{
p *= beta;
p += r; //z;
}
template<class TMatrix, class TVector>
inline void CGLinearSolver<TMatrix,TVector>::cgstep_alpha(Vector& x, Vector& r, Vector& p, Vector& q, double alpha)
{
x.peq(p,alpha); // x = x + alpha p
r.peq(q,-alpha); // r = r - alpha q
}
template<>
inline void CGLinearSolver<component::linearsolver::GraphScatteredMatrix,component::linearsolver::GraphScatteredVector>::cgstep_beta(Vector& p, Vector& r, double beta)
{
this->v_op(p,r,p,beta); // p = p*beta + r
}
template<>
inline void CGLinearSolver<component::linearsolver::GraphScatteredMatrix,component::linearsolver::GraphScatteredVector>::cgstep_alpha(Vector& x, Vector& r, Vector& p, Vector& q, double alpha)
{
#if 1 //SOFA_NO_VMULTIOP // unoptimized version
x.peq(p,alpha); // x = x + alpha p
r.peq(q,-alpha); // r = r - alpha q
#else // single-operation optimization
typedef core::componentmodel::behavior::BaseMechanicalState::VMultiOp VMultiOp;
VMultiOp ops;
ops.resize(2);
ops[0].first = (VecId)x;
ops[0].second.push_back(std::make_pair((VecId)x,1.0));
ops[0].second.push_back(std::make_pair((VecId)p,alpha));
ops[1].first = (VecId)r;
ops[1].second.push_back(std::make_pair((VecId)r,1.0));
ops[1].second.push_back(std::make_pair((VecId)q,-alpha));
simulation::tree::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
#endif
}
} // namespace linearsolver
} // namespace component
} // namespace sofa
#endif
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