se_stat.hxx

// Copyright (C) 2004  EPITA Research and Development Laboratory
//
// This file is part of the Olena Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License version 2 as published by the
// Free Software Foundation.
//
// This 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 library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free
// software library 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 OLN_UTILS_SE_STAT_HXX
# define OLN_UTILS_SE_STAT_HXX

namespace oln {
  namespace utils {

    template <typename Sum, typename Var>
    template <class I, class S>
    inline se_stat<Sum, Var> &
    se_stat<Sum, Var>::compute(const oln::abstract::image<I> &im,
                               const oln_point_type(I) &p,
                               const oln::abstract::struct_elt<S> &s)
    {
      sum_ = ntg_zero_val(Sum);
      card_ = s.card();
      // Compute the mean
      oln_iter_type(S) it(s);
      {
        for_all(it)
          sum_ += internal::f_to_float_<Sum,
          oln_value_type(I)>::doit(im[p + it]);
        mean_ = sum_ / card_;
      }
      // Compute the variance
      {
        Var sum_2(ntg_zero_val(Var));
        for_all(it)
          {
            Sum tmp = mean_;
            tmp -= im[p + it];
            sum_2 += oln::math::dot_product<Var>(tmp, tmp);
          }
        variance_ = sum_2 / card_;
      }
      return *this;
    }
  } // end namespace utils

} // end namespace oln

#endif 

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