AbstractBackwardEulerCardiacCell.hpp

/*

Copyright (C) University of Oxford, 2005-2009

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 ABSTRACTBACKWARDEULERCARDIACCELL_HPP_
#define ABSTRACTBACKWARDEULERCARDIACCELL_HPP_

#include "AbstractCardiacCell.hpp"
//#include "CardiacNewtonSolver.hpp"

#include <cassert>
#include <cmath>

template<unsigned SIZE>
class AbstractBackwardEulerCardiacCell : public AbstractCardiacCell
{
public:

    AbstractBackwardEulerCardiacCell(
        unsigned numberOfStateVariables,
        unsigned voltageIndex,
        AbstractStimulusFunction* intracellularStimulus);

    virtual ~AbstractBackwardEulerCardiacCell();

    virtual void ComputeResidual(const double rCurrentGuess[SIZE], double rResidual[SIZE])=0;

    virtual void ComputeJacobian(const double rCurrentGuess[SIZE], double rJacobian[SIZE][SIZE])=0;

    virtual OdeSolution Compute(double tStart, double tEnd);

    virtual void ComputeExceptVoltage(double tStart, double tEnd);

private:
#define COVERAGE_IGNORE

    void EvaluateYDerivatives(double time, const std::vector<double> &rY, std::vector<double> &rDY)
    {
        NEVER_REACHED;
    }
#undef COVERAGE_IGNORE

protected:
    virtual void ComputeOneStepExceptVoltage(double tStart)=0;

    virtual void UpdateTransmembranePotential(double time)=0;
};

template <unsigned SIZE>
AbstractBackwardEulerCardiacCell<SIZE>::AbstractBackwardEulerCardiacCell(
    unsigned numberOfStateVariables,
    unsigned voltageIndex,
    AbstractStimulusFunction* intracellularStimulus)
        : AbstractCardiacCell(NULL,
                              numberOfStateVariables,
                              voltageIndex,
                              intracellularStimulus)
{}

template <unsigned SIZE>
AbstractBackwardEulerCardiacCell<SIZE>::~AbstractBackwardEulerCardiacCell()
{}

template <unsigned SIZE>
OdeSolution AbstractBackwardEulerCardiacCell<SIZE>::Compute(double tStart, double tEnd)
{
    // In this method, we iterate over timesteps, doing the following for each:
    //   - update V using a forward Euler step
    //   - call ComputeExceptVoltage(t) to update the remaining state variables
    //     using backward Euler
    // Check length of time interval
    double _n_steps = (tEnd - tStart) / mDt;
    unsigned n_steps = (unsigned) round(_n_steps);
    assert(fabs(tStart+n_steps*mDt - tEnd) < 1e-12);

    // Initialise solution store
    OdeSolution solutions;
    solutions.SetNumberOfTimeSteps(n_steps);
    solutions.rGetSolutions().push_back(rGetStateVariables());
    solutions.rGetTimes().push_back(tStart);

    // Loop over time
    double curr_time;
    for (unsigned i=0; i<n_steps; i++)
    {
        curr_time = tStart + i*mDt;

        // Compute next value of V
        UpdateTransmembranePotential(curr_time);

        // Compute other state variables
        ComputeOneStepExceptVoltage(curr_time);

        // Update solutions
        solutions.rGetSolutions().push_back(rGetStateVariables());
        solutions.rGetTimes().push_back(curr_time+mDt);

        // check gating variables are still in range
        VerifyStateVariables();
    }

    return solutions;
}

template <unsigned SIZE>
void AbstractBackwardEulerCardiacCell<SIZE>::ComputeExceptVoltage(double tStart, double tEnd)
{
    // This method iterates over timesteps, calling ComputeExceptVoltage(t) at
    // each one, to update all state variables except for V, using backward Euler.
    // Check length of time interval
    double _n_steps = (tEnd - tStart) / mDt;
    unsigned n_steps = (unsigned) round(_n_steps);
    assert(fabs(tStart+n_steps*mDt - tEnd) < 1e-12);

    // Loop over time
    double curr_time;
    for (unsigned i=0; i<n_steps; i++)
    {
        curr_time = tStart + i*mDt;

        // Compute other state variables
        ComputeOneStepExceptVoltage(curr_time);

        // check gating variables are still in range
        VerifyStateVariables();
    }
}


#endif /*ABSTRACTBACKWARDEULERCARDIACCELL_HPP_*/

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