AbstractDynamicLinearPdeSolver.hpp

/*

Copyright (C) University of Oxford, 2005-2011

University of Oxford means the Chancellor, Masters and Scholars of the
University of Oxford, having an administrative office at Wellington
Square, Oxford OX1 2JD, UK.

This file is part of Chaste.

Chaste 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.

Chaste 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. The offer of Chaste under the terms of the
License is subject to the License being interpreted in accordance with
English Law and subject to any action against the University of Oxford
being under the jurisdiction of the English Courts.

You should have received a copy of the GNU Lesser General Public License
along with Chaste. If not, see <http://www.gnu.org/licenses/>.

*/

#ifndef ABSTRACTDYNAMICLINEARPDESOLVER_HPP_
#define ABSTRACTDYNAMICLINEARPDESOLVER_HPP_

#include "TimeStepper.hpp"
#include "AbstractLinearPdeSolver.hpp"
#include "PdeSimulationTime.hpp"
#include "AbstractTimeAdaptivityController.hpp"


template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
class AbstractDynamicLinearPdeSolver : public AbstractLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>
{
    friend class TestSimpleLinearParabolicSolver;

protected:
    double mTstart;

    double mTend;

    bool mTimesSet;

    Vec mInitialCondition;

    bool mMatrixIsAssembled;

    bool mMatrixIsConstant;

    double mIdealTimeStep;
    
    double mLastWorkingTimeStep;

    AbstractTimeAdaptivityController* mpTimeAdaptivityController;

public:
    AbstractDynamicLinearPdeSolver(AbstractTetrahedralMesh<ELEMENT_DIM,SPACE_DIM>* pMesh);

    void SetTimes(double tStart, double tEnd);

    void SetTimeStep(double dt);

    void SetInitialCondition(Vec initialCondition);

    Vec Solve();

    void SetMatrixIsNotAssembled()
    {
        mMatrixIsAssembled = false;
    }
    
    void SetTimeAdaptivityController(AbstractTimeAdaptivityController* pTimeAdaptivityController)
    {
        assert(pTimeAdaptivityController != NULL);
        assert(mpTimeAdaptivityController == NULL);
        mpTimeAdaptivityController = pTimeAdaptivityController;
    }
};    


template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
AbstractDynamicLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>::AbstractDynamicLinearPdeSolver(AbstractTetrahedralMesh<ELEMENT_DIM,SPACE_DIM>* pMesh)
    : AbstractLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>(pMesh),
      mTimesSet(false),
      mInitialCondition(NULL),
      mMatrixIsAssembled(false),
      mMatrixIsConstant(false),
      mIdealTimeStep(-1.0),
      mLastWorkingTimeStep(-1),
      mpTimeAdaptivityController(NULL)
{
}

template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
void AbstractDynamicLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>::SetTimes(double tStart, double tEnd)
{
    mTstart = tStart;
    mTend   = tEnd;

    if (mTstart >= mTend)
    {
        EXCEPTION("Starting time has to less than ending time");
    }

    mTimesSet = true;
}

template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
void AbstractDynamicLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>::SetTimeStep(double dt)
{
    if (dt <= 0)
    {
        EXCEPTION("Time step has to be greater than zero");
    }

    mIdealTimeStep = dt;
}

template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
void AbstractDynamicLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>::SetInitialCondition(Vec initialCondition)
{
    assert(initialCondition!=NULL);
    mInitialCondition = initialCondition;
}

template<unsigned ELEMENT_DIM, unsigned SPACE_DIM, unsigned PROBLEM_DIM>
Vec AbstractDynamicLinearPdeSolver<ELEMENT_DIM, SPACE_DIM, PROBLEM_DIM>::Solve()
{
    assert(mTimesSet);
    assert(mIdealTimeStep > 0.0 || mpTimeAdaptivityController);
    assert(mInitialCondition != NULL);

    this->InitialiseForSolve(mInitialCondition);

    if(mIdealTimeStep < 0) // hasn't been set, so a controller must have been given
    {
        mIdealTimeStep = mpTimeAdaptivityController->GetNextTimeStep(mTstart, mInitialCondition);
    }

    // Note: we use the mIdealTimeStep here (the original timestep that was passed in, or
    // the last timestep suggested by the controller), rather than the last timestep used
    // (mLastWorkingTimeStep), because the timestep will be very slightly altered by
    // the stepper in the final timestep of the last printing-timestep-loop, and these
    // floating point errors can add up and eventually cause exceptions being thrown.
    TimeStepper stepper(mTstart, mTend, mIdealTimeStep, mMatrixIsConstant);

    Vec current_solution = mInitialCondition;
    Vec next_solution;

    while ( !stepper.IsTimeAtEnd() )
    {    
        bool timestep_changed = false;

        PdeSimulationTime::SetTime(stepper.GetTime());
        
        // determine timestep to use 
        double new_dt;
        if (mpTimeAdaptivityController)
        {
            // get the timestep the controller wants to use and store it as the ideal timestep
            mIdealTimeStep = mpTimeAdaptivityController->GetNextTimeStep(stepper.GetTime(), current_solution);
            // tell the stepper to use this timestep from now on.
            stepper.ResetTimeStep(mIdealTimeStep);
            // ..but now get the timestep from the stepper, as the stepper might need
            // to trim the timestep if it would take us over the end time
            new_dt = stepper.GetNextTimeStep();

            timestep_changed = (fabs(mLastWorkingTimeStep-new_dt) > 1e-8);
        }
        else
        {
            new_dt = stepper.GetNextTimeStep();
        }

        // save the timestep as the last one use, and also put it in PdeSimulationTime
        // so everyone can see it
        mLastWorkingTimeStep = new_dt;
        PdeSimulationTime::SetPdeTimeStep( new_dt ); 

        // solve 

        this->PrepareForSetupLinearSystem(current_solution);

        bool compute_matrix = (!mMatrixIsConstant || !mMatrixIsAssembled || timestep_changed);
//        if (compute_matrix) std::cout << " ** ASSEMBLING MATRIX!!! ** " << std::endl;
        this->SetupLinearSystem(current_solution, compute_matrix);
       
        this->FinaliseLinearSystem(current_solution);
        
        if (compute_matrix)
        {
            this->mpLinearSystem->ResetKspSolver();
        }
    
        next_solution = this->mpLinearSystem->Solve(current_solution);

        if (mMatrixIsConstant)
        {
            mMatrixIsAssembled = true;
        }

        this->FollowingSolveLinearSystem(next_solution);

        stepper.AdvanceOneTimeStep();

        // Avoid memory leaks
        if (current_solution != mInitialCondition)
        {
            HeartEventHandler::BeginEvent(HeartEventHandler::COMMUNICATION);
            VecDestroy(current_solution);
            HeartEventHandler::EndEvent(HeartEventHandler::COMMUNICATION);
        }
        current_solution = next_solution;
    }    
    
    return current_solution;
}


#endif /*ABSTRACTDYNAMICLINEARPDESOLVER_HPP_*/

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