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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/RungeKutta2Solver.h>
#include <sofa/simulation/common/MechanicalVisitor.h>
#include <sofa/core/ObjectFactory.h>
#include <math.h>
#include <iostream>
namespace sofa
{
namespace component
{
namespace odesolver
{
using namespace core::componentmodel::behavior;
using namespace sofa::defaulttype;
int RungeKutta2SolverClass = core::RegisterObject("A popular explicit time integrator")
.add< RungeKutta2Solver >()
.addAlias("RungeKutta2")
;
SOFA_DECL_CLASS(RungeKutta2);
void RungeKutta2Solver::solve(double dt)
{
// Get the Ids of the state vectors
MultiVector pos(this, VecId::position());
MultiVector vel(this, VecId::velocity());
// Allocate auxiliary vectors
MultiVector acc(this, VecId::V_DERIV);
MultiVector newX(this, VecId::V_COORD);
MultiVector newV(this, VecId::V_DERIV);
double startTime = this->getTime();
addSeparateGravity(dt); // v += dt*g . Used if mass wants to added G separately from the other forces to v.
// Compute state derivative. vel is the derivative of pos
computeAcc (startTime, acc, pos, vel); // acc is the derivative of vel
// Perform a dt/2 step along the derivative
#ifdef SOFA_NO_VMULTIOP // unoptimized version
newX = pos;
newX.peq(vel, dt/2.); // newX = pos + vel dt/2
newV = vel;
newV.peq(acc, dt/2.); // newV = vel + acc dt/2
#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)vel,dt/2));
ops[1].first = (VecId)newV;
ops[1].second.push_back(std::make_pair((VecId)vel,1.0));
ops[1].second.push_back(std::make_pair((VecId)acc,dt/2));
simulation::MechanicalVMultiOpVisitor vmop(ops);
vmop.execute(this->getContext());
}
#endif
// Compute the derivative at newX, newV
computeAcc ( startTime+dt/2., acc, newX, newV);
// Use the derivative at newX, newV to update the state
#ifdef SOFA_NO_VMULTIOP // unoptimized version
pos.peq(newV,dt);
vel.peq(acc,dt);
#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)newV,dt));
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)acc,dt));
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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