RungeKutta2IvpOdeSolver.cpp

/*

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*/


#include "RungeKutta2IvpOdeSolver.hpp"

void RungeKutta2IvpOdeSolver::CalculateNextYValue(AbstractOdeSystem* pAbstractOdeSystem,
                                                  double timeStep,
                                                  double time,
                                                  std::vector<double>& rCurrentYValues,
                                                  std::vector<double>& rNextYValues)
{
    /*
     * Apply Runge-Kutta 2nd order method for each timestep in AbstractOneStepIvpSolver.
     * Calculates a vector containing the next Y value from the current one for each
     * equation in the system.
     */

    const unsigned num_equations = pAbstractOdeSystem->GetNumberOfStateVariables();

    std::vector<double> k1(num_equations);
    std::vector<double>& dy = rNextYValues; // re-use memory

    // Work out k1
    pAbstractOdeSystem->EvaluateYDerivatives(time, rCurrentYValues, dy);

    for (unsigned i=0; i<num_equations; i++)
    {
        k1[i] = timeStep*dy[i];
        k1[i] = k1[i]/2.0 + rCurrentYValues[i];
    }

    // Work out k2 and new solution
    pAbstractOdeSystem->EvaluateYDerivatives(time+timeStep/2.0, k1, dy);
    for (unsigned i=0; i<num_equations; i++)
    {
        rNextYValues[i] = rCurrentYValues[i] + timeStep*dy[i];
    }
}


// Serialization for Boost >= 1.36
#include "SerializationExportWrapperForCpp.hpp"
CHASTE_CLASS_EXPORT(RungeKutta2IvpOdeSolver)