RungeKutta< IntegrandClass, T > Class Template Reference

Collaboration diagram for RungeKutta< IntegrandClass, T >:

Public Member Functions
void	Integrate (const Grid &grid, int startPoint, int endPoint, Array< T, 1 > &result, bool scale=true)
	RungeKutta (IntegrandClass &integrand)

Private Member Functions
void	IntegrateForw (const Grid &grid, int startPoint, int endPoint, Array< T, 1 > &result, bool scale=true)
void	IntegrateRev (const Grid &grid, int startPoint, int endPoint, Array< T, 1 > &result, bool scale=true)

Private Attributes
IntegrandClass &	Integrand

Detailed Description

template<class IntegrandClass, class T>
class RungeKutta< IntegrandClass, T >

Definition at line 29 of file RungeKutta.h.

Constructor & Destructor Documentation

RungeKutta()

RungeKutta ( IntegrandClass &  integrand )

inline

Definition at line 101 of file RungeKutta.h.

                                        : Integrand(integrand)
  {
    // Do nothing
  }

Member Function Documentation

Integrate()

void Integrate ( const Grid &  grid, int  startPoint, int  endPoint, Array< T, 1 > &  result, bool  scale = true  )

inline

Definition at line 93 of file RungeKutta.h.

References RungeKutta< IntegrandClass, T >::IntegrateForw(), and RungeKutta< IntegrandClass, T >::IntegrateRev().

  {
    if (endPoint > startPoint)
      IntegrateForw(grid, startPoint, endPoint, result, scale);
    else
      IntegrateRev(grid, startPoint, endPoint, result, scale);
  }

IntegrateForw()

void IntegrateForw ( const Grid &  grid, int  startPoint, int  endPoint, Array< T, 1 > &  result, bool  scale = true  )

inlineprivate

Definition at line 35 of file RungeKutta.h.

References RungeKutta< IntegrandClass, T >::Integrand, and mag().

Referenced by RungeKutta< IntegrandClass, T >::Integrate().

  {
    T k1, k2, k3, k4;
    T y, yplus;
    double h, x;

    const static double OneSixth = 1.0 / 6.0;
    const static double OneThird = 1.0 / 3.0;

    for (int i = startPoint; i < endPoint; i++)
    {
      x             = grid(i);
      h             = grid(i + 1) - x;
      y             = result(i);
      k1            = h * Integrand(x, y);
      yplus         = y + 0.5 * k1;
      k2            = h * Integrand(x + 0.5 * h, yplus);
      yplus         = y + 0.5 * k2;
      k3            = h * Integrand(x + 0.5 * h, yplus);
      yplus         = y + k3;
      k4            = h * Integrand(x + h, yplus);
      result(i + 1) = y + (OneSixth * (k1 + k4) + OneThird * (k2 + k3));
      if (scale && mag(result(i + 1)) > 1.0e10)
        for (int j = startPoint; j <= endPoint; j++)
          result(j) *= 1.0e-10;
    }
  }

IntegrateRev()

void IntegrateRev ( const Grid &  grid, int  startPoint, int  endPoint, Array< T, 1 > &  result, bool  scale = true  )

inlineprivate

Definition at line 63 of file RungeKutta.h.

References RungeKutta< IntegrandClass, T >::Integrand, and mag().

Referenced by RungeKutta< IntegrandClass, T >::Integrate().

  {
    T k1, k2, k3, k4;
    T y, yplus;
    double h, x;

    const static double OneSixth = 1.0 / 6.0;
    const static double OneThird = 1.0 / 3.0;

    for (int i = startPoint; i > endPoint; i--)
    {
      x             = grid(i);
      h             = grid(i - 1) - x;
      y             = result(i);
      k1            = h * Integrand(x, y);
      yplus         = y + 0.5 * k1;
      k2            = h * Integrand(x + 0.5 * h, yplus);
      yplus         = y + 0.5 * k2;
      k3            = h * Integrand(x + 0.5 * h, yplus);
      yplus         = y + k3;
      k4            = h * Integrand(x + h, yplus);
      result(i - 1) = y + (OneSixth * (k1 + k4) + OneThird * (k2 + k3));
      if (scale && mag(result(i - 1)) > 1.0e10)
        for (int j = startPoint; j >= endPoint; j--)
          result(j) *= 1.0e-10;
    }
  }

Member Data Documentation

Integrand

IntegrandClass& Integrand

private

Definition at line 32 of file RungeKutta.h.

Referenced by RungeKutta< IntegrandClass, T >::IntegrateForw(), and RungeKutta< IntegrandClass, T >::IntegrateRev().

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The documentation for this class was generated from the following file:

• /home/pk7/projects/qmc/for_cron_doxygen/qmcpack/src/QMCTools/ppconvert/src/common/RungeKutta.h