source: trunk/yat/utility/SVD.cc @ 703

// $Id: SVD.cc 703 2006-12-18 00:47:44Z jari $

/*
  Copyright (C) The authors contributing to this file.

  This file is part of the yat library, http://lev.thep.lu.se/trac/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  The yat library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#include "SVD.h"

namespace theplu {
namespace yat {
namespace utility {


  SVD::SVD(const utility::matrix& Ain)
    : U_(Ain), V_(Ain.columns(),Ain.columns()), s_(Ain.columns())
  {
  }


  SVD::~SVD(void)
  {
  }


  int SVD::decompose(SVDalgorithm algo)
  {
    switch (algo) {
        case GolubReinsch:
          return golub_reinsch();
        case ModifiedGolubReinsch:
          return modified_golub_reinsch();
        case Jacobi:
          return jacobi();
    }
    // the program should never end up here, return values should be
    // something different from normal GSL return values, or maybe
    // throw an exception.
    return 0;
  }



  int SVD::golub_reinsch(void)
  {
    utility::vector w(U_.columns());
    return gsl_linalg_SV_decomp(U_.gsl_matrix_p(), V_.gsl_matrix_p(),
                                s_.gsl_vector_p(), w.gsl_vector_p());
  }



  int SVD::modified_golub_reinsch(void)
  {
    utility::vector w(U_.columns());
    utility::matrix X(U_.columns(),U_.columns());
    return gsl_linalg_SV_decomp_mod(U_.gsl_matrix_p(), X.gsl_matrix_p(), 
                                    V_.gsl_matrix_p(), s_.gsl_vector_p(),
                                    w.gsl_vector_p());
  }


}}} // of namespace utility, yat, and theplu