/*

Copyright (C) 2008-2016 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/>.

*/

// This is the octave interface to amd, which bore the copyright given
// in the help of the functions.

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <cstdlib>

#include <string>
#include <vector>

#include "ov.h"
#include "defun-dld.h"
#include "errwarn.h"
#include "pager.h"
#include "ov-re-mat.h"

#include "ov-re-sparse.h"
#include "ov-cx-sparse.h"
#include "oct-map.h"

#include "oct-sparse.h"
#include "oct-locbuf.h"

#if defined (OCTAVE_ENABLE_64)
#  define AMD_NAME(name) amd_l ## name
#else
#  define AMD_NAME(name) amd ## name
#endif

DEFUN_DLD (amd, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{p} =} amd (@var{S})
@deftypefnx {} {@var{p} =} amd (@var{S}, @var{opts})

Return the approximate minimum degree permutation of a matrix.

This is a permutation such that the Cholesky@tie{}factorization of
@code{@var{S} (@var{p}, @var{p})} tends to be sparser than the
Cholesky@tie{}factorization of @var{S} itself.  @code{amd} is typically
faster than @code{symamd} but serves a similar purpose.

The optional parameter @var{opts} is a structure that controls the behavior
of @code{amd}.  The fields of the structure are

@table @asis
@item @var{opts}.dense
Determines what @code{amd} considers to be a dense row or column of the
input matrix.  Rows or columns with more than @code{max (16, (dense *
sqrt (@var{n})))} entries, where @var{n} is the order of the matrix @var{S},
are ignored by @code{amd} during the calculation of the permutation.
The value of dense must be a positive scalar and the default value is 10.0

@item @var{opts}.aggressive
If this value is a nonzero scalar, then @code{amd} performs aggressive
absorption.  The default is not to perform aggressive absorption.
@end table

The author of the code itself is Timothy A. Davis
@email{davis@@cise.ufl.edu}, University of Florida
(see @url{http://www.cise.ufl.edu/research/sparse/amd}).
@seealso{symamd, colamd}
@end deftypefn */)
{
#if defined (HAVE_AMD)

  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  octave_idx_type n_row, n_col;
  const octave_idx_type *ridx, *cidx;
  SparseMatrix sm;
  SparseComplexMatrix scm;

  if (args(0).is_sparse_type ())
    {
      if (args(0).is_complex_type ())
        {
          scm = args(0).sparse_complex_matrix_value ();
          n_row = scm.rows ();
          n_col = scm.cols ();
          ridx = scm.xridx ();
          cidx = scm.xcidx ();
        }
      else
        {
          sm = args(0).sparse_matrix_value ();
          n_row = sm.rows ();
          n_col = sm.cols ();
          ridx = sm.xridx ();
          cidx = sm.xcidx ();
        }
    }
  else
    {
      if (args(0).is_complex_type ())
        sm = SparseMatrix (real (args(0).complex_matrix_value ()));
      else
        sm = SparseMatrix (args(0).matrix_value ());

      n_row = sm.rows ();
      n_col = sm.cols ();
      ridx = sm.xridx ();
      cidx = sm.xcidx ();
    }

  if (n_row != n_col)
    err_square_matrix_required ("amd", "S");

  OCTAVE_LOCAL_BUFFER (double, Control, AMD_CONTROL);
  AMD_NAME (_defaults) (Control);
  if (nargin > 1)
    {
      octave_scalar_map arg1 = args(1).xscalar_map_value ("amd: OPTS argument must be a scalar structure");

      octave_value tmp;

      tmp = arg1.getfield ("dense");
      if (tmp.is_defined ())
        Control[AMD_DENSE] = tmp.double_value ();

      tmp = arg1.getfield ("aggressive");
      if (tmp.is_defined ())
        Control[AMD_AGGRESSIVE] = tmp.double_value ();
    }

  OCTAVE_LOCAL_BUFFER (octave_idx_type, P, n_col);
  Matrix xinfo (AMD_INFO, 1);
  double *Info = xinfo.fortran_vec ();

  // FIXME: how can we manage the memory allocation of amd
  //        in a cleaner manner?
  SUITESPARSE_ASSIGN_FPTR (malloc_func, amd_malloc, malloc);
  SUITESPARSE_ASSIGN_FPTR (free_func, amd_free, free);
  SUITESPARSE_ASSIGN_FPTR (calloc_func, amd_calloc, calloc);
  SUITESPARSE_ASSIGN_FPTR (realloc_func, amd_realloc, realloc);
  SUITESPARSE_ASSIGN_FPTR (printf_func, amd_printf, printf);

  octave_idx_type result = AMD_NAME (_order) (n_col, cidx, ridx, P,
                                              Control, Info);

  if (result == AMD_OUT_OF_MEMORY)
    error ("amd: out of memory");
  else if (result == AMD_INVALID)
    error ("amd: matrix S is corrupted");

  Matrix Pout (1, n_col);
  for (octave_idx_type i = 0; i < n_col; i++)
    Pout.xelem (i) = P[i] + 1;

  if (nargout > 1)
    return ovl (Pout, xinfo);
  else
    return ovl (Pout);

#else

  octave_unused_parameter (args);
  octave_unused_parameter (nargout);

  err_disabled_feature ("amd", "AMD");

#endif
}

/*
%!shared A, A2, opts
%! A = ones (20, 30);
%! A2 = ones (30, 30);
%!
%!testif HAVE_AMD
%! assert(amd (A2), [1:30]);
%! opts.dense = 25;
%! assert(amd (A2, opts), [1:30]);
%! opts.aggressive = 1;
%! assert(amd (A2, opts), [1:30]);

%!error <S must be a square matrix|was unavailable or disabled> amd (A)
%!error amd (A2, 2)
%!error <matrix S is corrupted|was unavailable or disabled> amd ([])
*/

