/*

Copyright (C) 2007-2015 David Bateman

This file is part of Octave.

Octave 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.

Octave 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 Octave; see the file COPYING.  If not, see
<http://www.gnu.org/licenses/>.

*/

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <iostream>
#include <fstream>
#include <string>

#include "lo-math.h"

#include "defun.h"
#include "error.h"
#include "ovl.h"

DEFUN (__dsearchn__, args, ,
       "-*- texinfo -*-\n\
@deftypefn {} {[@var{idx}, @var{d}] =} dsearch (@var{x}, @var{xi})\n\
Undocumented internal function.\n\
@end deftypefn")
{
  if (args.length () != 2)
    print_usage ();

  Matrix x = args(0).matrix_value ().transpose ();
  Matrix xi = args(1).matrix_value ().transpose ();

  if (x.rows () != xi.rows () || x.columns () < 1)
    error ("__dsearch__: number of rows of X and XI must match");

  octave_idx_type n = x.rows ();
  octave_idx_type nx = x.columns ();
  octave_idx_type nxi = xi.columns ();

  ColumnVector idx (nxi);
  double *pidx = idx.fortran_vec ();
  ColumnVector dist (nxi);
  double *pdist = dist.fortran_vec ();

#define DIST(dd, y, yi, m) \
  dd = 0.0; \
  for (octave_idx_type k = 0; k < m; k++) \
    { \
      double yd = y[k] - yi[k]; \
      dd += yd * yd; \
    } \
  dd = sqrt (dd)

  const double *pxi = xi.fortran_vec ();
  for (octave_idx_type i = 0; i < nxi; i++)
    {
      double d0;
      const double *px = x.fortran_vec ();
      DIST(d0, px, pxi, n);
      *pidx = 1.;
      for (octave_idx_type j = 1; j < nx; j++)
        {
          px += n;
          double d;
          DIST (d, px, pxi, n);
          if (d < d0)
            {
              d0 = d;
              *pidx = static_cast<double>(j + 1);
            }
          OCTAVE_QUIT;
        }

      *pdist++ = d0;
      pidx++;
      pxi += n;
    }

  return ovl (idx, dist);
}

/*
## No test needed for internal helper function.
%!assert (1)
*/