ScaledMatrix.h

#ifndef _theplu_yat_utility_expression_scaled_matrix
#define _theplu_yat_utility_expression_scaled_matrix

// $Id: ScaledMatrix.h 3908 2020-05-13 06:58:38Z peter $

/*
  Copyright (C) 2020 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/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 3 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 yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include "yat/utility/BasicMatrix.h"
#include "yat/utility/BLAS_utility.h"
#include "yat/utility/MatrixExpression.h"

#include <gsl/gsl_matrix.h>

namespace theplu {
namespace yat {
namespace utility {
namespace expression {


  template<class T>
  class ScaledMatrix : public MatrixExpression<ScaledMatrix<T> >
  {
  public:
    ScaledMatrix(double factor, const BasicMatrix<T>& A)
      : A_(A), factor_(factor) {}

    size_t rows(void) const { return A_.rows(); }
    size_t columns(void) const { return A_.columns(); }


    double operator()(size_t i, size_t j) const
    {
      return factor_ * A_(i, j);
    }


    const T& base(void) const
    {
      return static_cast<const T&>(A_);
    }


    void calculate_matrix(gsl_matrix*& result) const
    {
      detail::copy(result, A_.gsl_matrix_p());
      gsl_matrix_scale(result, factor_);
    }


    double factor(void) const
    {
      return factor_;
    }

  private:
    const BasicMatrix<T>& A_;
    double factor_;
  };

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

#endif