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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 *
******************************************************************************/
#include <sofa/component/odesolver/RungeKutta4Solver.h>
#include <sofa/simulation/common/MechanicalVisitor.h>
#include <sofa/core/ObjectFactory.h>
#include <math.h>
namespace sofa
{
namespace component
{
namespace odesolver
{
using namespace core::componentmodel::behavior;
using namespace sofa::defaulttype;
int RungeKutta4SolverClass = core::RegisterObject("A popular explicit time integrator")
.add< RungeKutta4Solver >()
.addAlias("RungeKutta4")
;
SOFA_DECL_CLASS(RungeKutta4);
void RungeKutta4Solver::solve(double dt)
{
//sout << "RK4 Init"<<sendl;
MultiVector pos(this, VecId::position());
MultiVector vel(this, VecId::velocity());
MultiVector k1a(this, VecId::V_DERIV);
MultiVector k2a(this, VecId::V_DERIV);
MultiVector k3a(this, VecId::V_DERIV);
MultiVector k4a(this, VecId::V_DERIV);
MultiVector& k1v = vel; //(this, VecId::V_DERIV);
MultiVector k2v(this, VecId::V_DERIV);
MultiVector k3v(this, VecId::V_DERIV);
MultiVector k4v(this, VecId::V_DERIV);
MultiVector newX(this, VecId::V_COORD);
//MultiVector newV(this, VecId::V_DERIV);
const bool log = this->f_printLog.getValue();
double stepBy2 = double(dt / 2.0);
double stepBy3 = double(dt / 3.0);
double stepBy6 = double(dt / 6.0);
double startTime = this->getTime();
addSeparateGravity(dt); // v += dt*g . Used if mass wants to added G separately from the other forces to v.
//First step
if (log) sout << "RK4 Step 1"<<sendl;
//k1v = vel;
computeAcc (startTime, k1a, pos, vel);
//Step 2
if (log) sout << "RK4 Step 2"<<sendl;
#ifdef SOFA_NO_VMULTIOP // unoptimized version
newX = pos;
k2v = vel;
newX.peq(k1v, stepBy2);
k2v.peq(k1a, stepBy2);
#else // single-operation optimization
{
typedef core::componentmodel::behavior::BaseMechanicalState::VMultiOp VMultiOp;
VMultiOp ops;
ops.resize(2);
ops[0].first = (VecId)newX;
ops[0].second.push_back(std::make_pair((VecId)pos,1.0));
ops[0].second.push_back(std::make_pair((VecId)k1v,stepBy2));
ops[1].first = (VecId)k2v;
ops[1].second.push_back(std::make_pair((VecId)vel,1.0));
ops[1].second.push_back(std::make_pair((VecId)k1a,stepBy2));
simulation::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
}
#endif
computeAcc ( startTime+stepBy2, k2a, newX, k2v );
// step 3
if (log) sout << "RK4 Step 3"<<sendl;
#ifdef SOFA_NO_VMULTIOP // unoptimized version
newX = pos;
k3v = vel;
newX.peq(k2v, stepBy2);
k3v.peq(k2a, stepBy2);
#else // single-operation optimization
{
typedef core::componentmodel::behavior::BaseMechanicalState::VMultiOp VMultiOp;
VMultiOp ops;
ops.resize(2);
ops[0].first = (VecId)newX;
ops[0].second.push_back(std::make_pair((VecId)pos,1.0));
ops[0].second.push_back(std::make_pair((VecId)k2v,stepBy2));
ops[1].first = (VecId)k3v;
ops[1].second.push_back(std::make_pair((VecId)vel,1.0));
ops[1].second.push_back(std::make_pair((VecId)k2a,stepBy2));
simulation::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
}
#endif
computeAcc ( startTime+stepBy2, k3a, newX, k3v );
// step 4
if (log) sout << "RK4 Step 4"<<sendl;
#ifdef SOFA_NO_VMULTIOP // unoptimized version
newX = pos;
k4v = vel;
newX.peq(k3v, dt);
k4v.peq(k3a, dt);
#else // single-operation optimization
{
typedef core::componentmodel::behavior::BaseMechanicalState::VMultiOp VMultiOp;
VMultiOp ops;
ops.resize(2);
ops[0].first = (VecId)newX;
ops[0].second.push_back(std::make_pair((VecId)pos,1.0));
ops[0].second.push_back(std::make_pair((VecId)k3v,dt));
ops[1].first = (VecId)k4v;
ops[1].second.push_back(std::make_pair((VecId)vel,1.0));
ops[1].second.push_back(std::make_pair((VecId)k3a,dt));
simulation::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
}
#endif
computeAcc( startTime+dt, k4a, newX, k4v);
if (log) sout << "RK4 Final"<<sendl;
#ifdef SOFA_NO_VMULTIOP // unoptimized version
pos.peq(k1v,stepBy6);
vel.peq(k1a,stepBy6);
pos.peq(k2v,stepBy3);
vel.peq(k2a,stepBy3);
pos.peq(k3v,stepBy3);
vel.peq(k3a,stepBy3);
pos.peq(k4v,stepBy6);
vel.peq(k4a,stepBy6);
#else // single-operation optimization
{
typedef core::componentmodel::behavior::BaseMechanicalState::VMultiOp VMultiOp;
VMultiOp ops;
ops.resize(2);
ops[0].first = (VecId)pos;
ops[0].second.push_back(std::make_pair((VecId)pos,1.0));
ops[0].second.push_back(std::make_pair((VecId)k1v,stepBy6));
ops[0].second.push_back(std::make_pair((VecId)k2v,stepBy3));
ops[0].second.push_back(std::make_pair((VecId)k3v,stepBy3));
ops[0].second.push_back(std::make_pair((VecId)k4v,stepBy6));
ops[1].first = (VecId)vel;
ops[1].second.push_back(std::make_pair((VecId)vel,1.0));
ops[1].second.push_back(std::make_pair((VecId)k1a,stepBy6));
ops[1].second.push_back(std::make_pair((VecId)k2a,stepBy3));
ops[1].second.push_back(std::make_pair((VecId)k3a,stepBy3));
ops[1].second.push_back(std::make_pair((VecId)k4a,stepBy6));
simulation::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
}
#endif
#ifdef SOFA_HAVE_LAPACK
applyConstraints();
#endif
}
} // namespace odesolver
} // namespace component
} // namespace sofa
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