l2.hh

// Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena 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, version 2 of the License.
//
// Olena 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 Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_NORM_L2_HH
# define MLN_NORM_L2_HH


# include <mln/math/sqr.hh>
# include <mln/math/sqrt.hh>
# include <mln/algebra/vec.hh>
# include <mln/value/ops.hh>


namespace mln
{

  // Forward declaration.
  namespace algebra
  {
    template <unsigned n, typename T> class vec;
  }


  namespace norm
  {

    template <unsigned n, typename C>
    mln_sum_product(C,C) l2(const C (&vec)[n]);

    template <unsigned n, typename C>
    mln_sum_product(C,C) l2(const algebra::vec<n,C>& vec);

    template <unsigned n, typename C>
    mln_sum_product(C,C) sqr_l2(const C (&vec)[n]);

    template <unsigned n, typename C>
    mln_sum_product(C,C) sqr_l2(const algebra::vec<n,C>& vec);

    template <unsigned n, typename C>
    mln_sum_product(C,C) l2_distance(const C (&vec1)[n], const C (&vec2)[n]);

    template <unsigned n, typename C>
    mln_sum_product(C,C) l2_distance(const algebra::vec<n,C>& vec1,
                           const algebra::vec<n,C>& vec2);


# ifndef MLN_INCLUDE_ONLY

    namespace impl
    {

      template <unsigned n, typename C, typename V>
      inline
      mln_sum_product(C,C)
      l2_(const V& vec)
      {
        typedef mln_sum_product(C,C) M;
        M m = 0;
        for (unsigned i = 0; i < n; ++i)
          {
            M sqr_v_i = static_cast<M>(mln::math::sqr(vec[i]));
            m = static_cast<M>(m + sqr_v_i);
          }
        return mln::math::sqrt(m);
      }

      template <unsigned n, typename C, typename V>
      inline
      mln_sum_product(C,C)
      sqr_l2_(const V& vec)
      {
        mln_sum_product(C,C) m = 0;
        for (unsigned i = 0; i < n; ++i)
          m += mln::math::sqr(vec[i]);
        return m;
      }

      template <unsigned n, typename C, typename V>
      inline
      mln_sum_product(C,C)
      l2_distance_(const V& vec1, const V& vec2)
      {
        typedef mln_sum_product(C,C) D;
        D d = 0;
        for (unsigned i = 0; i < n; ++i)
          {
            D sqr_v1_v2 = static_cast<D>(mln::math::sqr(vec1[i] - vec2[i]));
            d = static_cast<D>(d + sqr_v1_v2);
          }
        return mln::math::sqrt(d);
      }

    } // end of namespace mln::norm::impl


    /*----------.
    | Facades.  |
    `----------*/

    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    l2(const C (&vec)[n])
    {
      return impl::l2_<n, C>(vec);
    }

    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    l2(const algebra::vec<n,C>& vec)
    {
      return impl::l2_<n, C>(vec);
    }


    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    sqr_l2(const C (&vec)[n])
    {
      return impl::sqr_l2_<n, C>(vec);
    }

    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    sqr_l2(const algebra::vec<n,C>& vec)
    {
      return impl::sqr_l2_<n, C>(vec);
    }


    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    l2_distance(const C (&vec1)[n], const C (&vec2)[n])
    {
      return impl::l2_distance_<n, C>(vec1, vec2);
    }

    template <unsigned n, typename C>
    inline
    mln_sum_product(C,C)
    l2_distance(const algebra::vec<n,C>& vec1, const algebra::vec<n,C>& vec2)
    {
      return impl::l2_distance_<n, C>(vec1, vec2);
    }

# endif // ! MLN_INCLUDE_ONLY

  } // end of namespace mln::norm

} // end of namespace mln


#endif // ! MLN_NORM_L2_HH