vtkRungeKutta45.h

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/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkRungeKutta45.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#ifndef vtkRungeKutta45_h
#define vtkRungeKutta45_h

#include "vtkCommonMathModule.h" // For export macro
#include "vtkInitialValueProblemSolver.h"

class VTKCOMMONMATH_EXPORT vtkRungeKutta45 : public vtkInitialValueProblemSolver
{
public:
  vtkTypeMacro(vtkRungeKutta45,vtkInitialValueProblemSolver);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  static vtkRungeKutta45 *New();


  int ComputeNextStep(double* xprev, double* xnext,
                      double t, double& delT,
                      double maxError, double& error) override
  {
      double minStep = delT;
      double maxStep = delT;
      double delTActual;
      return this->ComputeNextStep(xprev, nullptr, xnext, t, delT, delTActual,
                                   minStep, maxStep, maxError, error);
  }
  int ComputeNextStep(double* xprev, double* dxprev, double* xnext,
                      double t, double& delT,
                      double maxError, double& error) override
  {
      double minStep = delT;
      double maxStep = delT;
      double delTActual;
      return this->ComputeNextStep(xprev, dxprev, xnext, t, delT, delTActual,
                                   minStep, maxStep, maxError, error);
  }
  int ComputeNextStep(double* xprev, double* xnext,
                      double t, double& delT, double& delTActual,
                      double minStep, double maxStep,
                      double maxError, double& error) override
  {
      return this->ComputeNextStep(xprev, nullptr, xnext, t, delT, delTActual,
                                   minStep, maxStep, maxError, error);
  }
  int ComputeNextStep(double* xprev, double* dxprev, double* xnext,
                      double t, double& delT, double& delTActual,
                      double minStep, double maxStep,
                      double maxError, double& error) override;

protected:
  vtkRungeKutta45();
  ~vtkRungeKutta45() override;

  void Initialize() override;

  // Cash-Karp parameters
  static double A[5];
  static double B[5][5];
  static double C[6];
  static double DC[6];

  double* NextDerivs[6];

  int ComputeAStep(double* xprev, double* dxprev, double* xnext, double t,
                   double& delT,  double& delTActual, double& error);

private:
  vtkRungeKutta45(const vtkRungeKutta45&) = delete;
  void operator=(const vtkRungeKutta45&) = delete;
};

#endif