implicit_euler_integrator.h

/* Copyright (C) 2004-2009 MBSim Development Team
 *
 * 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
 *
 * Contact: martin.o.foerg@googlemail.com
 */
 
#ifndef _IMPLICIT_EULER_INTEGRATOR_H_
#define _IMPLICIT_EULER_INTEGRATOR_H_
 
#include "integrator.h"
#include "mbsim/functions/function.h"
 
namespace MBSim {
 
  class ImplicitEulerIntegrator : public Integrator {
 
    class Residuum : public MBSim::Function<fmatvec::Vec(fmatvec::Vec)> {
      public:
        Residuum(MBSim::DynamicSystemSolver *sys_, double dt_) : sys(sys_), dt(dt_) { }
        void setState(const fmatvec::Vec &zk_) { zk <<= zk_; }
      protected:
        MBSim::DynamicSystemSolver *sys;
        fmatvec::Vec zk;
        double dt;
    };
 
    class ResiduumFull : public Residuum {
      public:
        ResiduumFull(MBSim::DynamicSystemSolver *sys, double dt) : Residuum(sys, dt) { }
        fmatvec::Vec operator()(const fmatvec::Vec &z);
    };
 
    class ResiduumReduced : public Residuum {
      public:
        ResiduumReduced(MBSim::DynamicSystemSolver *sys, double dt) : Residuum(sys, dt) { }
        fmatvec::Vec operator()(const fmatvec::Vec &ux);
    };
 
    public:
      ~ImplicitEulerIntegrator() override = default;
 
      void preIntegrate() override;
      void subIntegrate(double tStop) override;
      void postIntegrate() override;
 
      /* INHERITED INTERFACE OF INTEGRATOR */
      using Integrator::integrate;
      void integrate() override;
      void initializeUsingXML(xercesc::DOMElement *element) override;
      /***************************************************/
 
      /* GETTER / SETTER */
      void setStepSize(double dt_) {dt = dt_;}
      void setReducedForm(bool reduced_) { reduced = reduced_; }
      /***************************************************/
 
    private:
      double dt{1e-3};
 
      bool reduced{false};
 
      double tPlot;
      int iter, step, integrationSteps;
      double s0, time;
      int stepPlot;
 
      Residuum *res{nullptr};
  };
 
}
 
#endif