#ifndef FILE_EIGEN
#define FILE_EIGEN

/**************************************************************************/
/* File:   eigen.hpp                                                      */
/* Author: Joachim Schoeberl                                              */
/* Date:   5. Jul. 96                                                     */
/**************************************************************************/

/**
   Lanczos Eigen system calculation
*/ 

class EigenSystem
{
  ///
const BaseMatrix *a, *c;
  ///
ARRAY<double> ai, bi;
  ///
double prec;
  ///
int maxsteps;
  
public:
  ///
  EigenSystem (const BaseMatrix & aa);
  ///
  EigenSystem (const BaseMatrix & aa, const BaseMatrix & ac);
  ///
  void SetMatrix (const BaseMatrix & aa);
  ///
  void SetPrecond (const BaseMatrix & ac);
  ///
  void SetMaxSteps (int amaxsteps);
  ///
  void SetPrecision (double aprec);

  ///
  void Calc();

  ///
  double EigenValue (int nr) const;
  ///
  double MaxEigenValue () const;
  ///
  int NumEigenValues () const;
  ///
  void PrintEigenValues (ostream & ost) const;
};

#endif