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RK2TMover.cpp

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// RK2TMover.cpp: implementation of the CRK2TMover class.
//

#include "RK2TMover.h"

// Construction/Destruction

CRK2TMover::CRK2TMover()
{

}

CRK2TMover::CRK2TMover(double frequency, double stepSize)
:CRungeKuttaMover(frequency,stepSize)
{

}

CRK2TMover::~CRK2TMover()
{

}

// This function takes a second-order trapezoidal RK step.

void CRK2TMover::RungeKuttaStep(int nRHS, double *y, double *dydt)
{
        int i;
        double *yTemp = new double[nRHS];
        double *dydtTemp = new double[nRHS];
        double halfStep = 0.5*m_dStepSize;
        
        // beginning of interval
        ComputeDerivatives(y,dydt);
        for(i = 0; i < nRHS; i++)
        {
                yTemp[i] = y[i] + halfStep*dydt[i];
        }
        
        // step forward
        ComputeDerivatives(yTemp,dydtTemp);

        // update y(t) to y(t+h)
        for(i = 0; i < nRHS; i++)
        {
                y[i] = y[i] + halfStep*(dydt[i] + dydtTemp[i]);
        }
        
        // free memory
        delete [] yTemp;
        delete [] dydtTemp;
}

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