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

  Program:   Visualization Toolkit
  Module:    vtkInitialValueProblemSolver.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

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   and/or other materials provided with the distribution.

 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

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   misrepresented as being the original software.

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=========================================================================*/
// .NAME vtkInitialValueProblemSolver - Integrate a set of ordinary
// differential equations (initial value problem) in time.

// .SECTION Description
// Given a vtkFunctionSet which returns dF_i(x_j, t)/dt given x_j and
// t, vtkInitialValueProblemSolver computes the value of F_i at t+deltat.

// .SECTION Warning
// vtkInitialValueProblemSolver and it's subclasses are not thread-safe.
// You should create a new integrator for each thread.

// .SECTION See Also
// vtkRungeKutta2 vtkRungeKutta4

#ifndef __vtkInitialValueProblemSolver_h
#define __vtkInitialValueProblemSolver_h

#include "vtkFunctionSet.h"

class VTK_EXPORT vtkInitialValueProblemSolver : public vtkObject
{
public:
  vtkTypeMacro(vtkInitialValueProblemSolver,vtkObject);
  virtual void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Given initial values, xprev , initial time, t and time interval, delT
  // calculate values of x at t+delT (xnext)
  // It returns an estimated value for the error (not implemented yet)
  // or -1 on failure (for example, if the integration moves out of
  // a data set)
  virtual float ComputeNextStep(float* xprev, float* xnext, float t,
				float delT) 
    {
      return this->ComputeNextStep(xprev, 0, xnext, t, delT);
    }
  virtual float ComputeNextStep(float* xprev, float* dxprev, float* xnext, 
				float t, float delT) = 0;

  // Description:
  // Create concrete instance of the object.
  virtual vtkInitialValueProblemSolver *MakeObject()=0;
  
  // Description:
  // Set / get the dataset used for the implicit function evaluation.
  virtual void SetFunctionSet(vtkFunctionSet* functionset);
  vtkGetObjectMacro(FunctionSet,vtkFunctionSet);

protected:
  vtkInitialValueProblemSolver();
  ~vtkInitialValueProblemSolver();
  vtkInitialValueProblemSolver(const vtkInitialValueProblemSolver&) {};
  void operator=(const vtkInitialValueProblemSolver&) {};

  virtual void Initialize();

  vtkFunctionSet* FunctionSet;

  float* Vals;
  float* Derivs;
  int Initialized;
};

#endif




