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// Copyright (C) 1998, 2000-2007, 2010, 2011, 2012 SINTEF ICT, Applied
// Mathematics, Norway.
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// SINTEF ICT, Department of Applied Mathematics,                         
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#ifndef _SOLVEBCG_H
#define _SOLVEBCG_H


#include "GoTools/creators/SolveCG.h"

namespace Go
{

  /// Using the biconjugate gradient method to solve sparse and
  /// positive definite matrix systems.

class SolveBCG : public SolveCG
{

public:

  /// Constructor.
  /// \param conv_type in the range 1 to 4. Convergence estimate. The selection
  /// of preconditioner is based on this number
  SolveBCG(int conv_type, bool symm);

  /// Destructor.
  virtual ~SolveBCG();

  /// Prepare for preconditioning.
  virtual void precond(double relaxfac);

  /// Solve the equation system.
  virtual int solve(double *ex, double *eb, int nn);


private:

  double omega_;        // Relaxation parameter.
  int conv_type_; // We operate with 4 different types of convergence estimates.
  bool symm_;

  void precondRILU(double relaxfac); // @@sbr Not sure RILU is what we will be using...

  // Helper funtion, return largest element in array (i.e. the sup-norm).
  double max_abs_element(double* x, int nn);

};

} // end namespace Go


#endif // _SOLVEBCG_H

