DoubleEigen.h

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#ifndef CLASSIC_DoubleEigen_HH
#define CLASSIC_DoubleEigen_HH

// ------------------------------------------------------------------------
// $RCSfile: DoubleEigen.h,v $
// ------------------------------------------------------------------------
// $Revision: 1.1.1.1 $
// ------------------------------------------------------------------------
// Copyright: see Copyright.readme
// ------------------------------------------------------------------------
//
// Class ComplexEigen:
//
// ------------------------------------------------------------------------
// Class category: Algebra
// ------------------------------------------------------------------------
//
// $Date: 2000/03/27 09:32:32 $
// $Author: fci $
//
// ------------------------------------------------------------------------

#include "Algebra/Matrix.h"
#include "Algebra/Vector.h"
#include <complex>

using std::complex;


// Class DoubleEigen
// ------------------------------------------------------------------------
//  Representation of eigenvalues and eigenvectors
//  for a matrix of type Matrix<double>.

class DoubleEigen {

public:

    //  Construct the vector of complex eigenvalues for the matrix [b]M[/b].
    //  If [b]vec[/b] is true, the matrix of eigenvectors is also built.
    DoubleEigen(const Matrix<double> &m, bool vec = false);

    DoubleEigen();
    DoubleEigen(const DoubleEigen &);
    ~DoubleEigen();

    //  Return the eigenvalues as a complex vector.
    Vector<complex<double> > eigenValues() const;

    //  Return the eigenvectors as the column vectors of a complex matrix.
    Matrix<complex<double> > eigenVectors() const;

    //  Return the eigenvectors packed in a real matrix.
    //  Real eigenvectors appear a single column in the same position as
    //  the corresponding real eigenvalue.
    //  Complex eigenvalues occur in conjugate pairs, and the corresponding
    //  eigenvectors appear as two real columns containing the real and
    //  imaginary parts respectively.
    Matrix<double> packedEigenVectors() const;

private:

    // Not implemented.
    void operator=(const DoubleEigen &);

    // Used by eigenvalue and eigenvector routines
    static void balance(Matrix<double> &, int &low, int &high,
                        Vector<double> &);

    static void exchange(Matrix<double> &, int j, int m,
                         int low, int high);

    static void elmhes(Matrix<double> &, int low, int high,
                       Array1D<int> &index);

    void elmtran(Matrix<double> &, int low, int high,
                 Array1D<int> &index);

    int hqr(Matrix<double> &, int low, int high);

    int hqr2(Matrix<double> &, int low, int high);

    void balbak(int low, int high, Vector<double> &scale);

    // Representation of the eigenvalues and eigenvectors.
    Vector<complex<double> > lambda;
    Matrix<double>           vectors;
};

#endif // CLASSIC_DoubleEigen_HH