/* 

Copyright (C) 2002, 2006, 2007 Kai Habel
Copyright (C) 2008, 2009 Jaroslav Hajek

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 "defun-dld.h"
#include "error.h"
#include "gripes.h"
#include "oct-obj.h"
#include "utils.h"
#include "f77-fcn.h"

extern "C"
{
  F77_RET_T
  F77_FUNC (dpchim, DPCHIM) (const octave_idx_type& n, const double *x, const double *f,
			     double *d, const octave_idx_type &incfd,
			     octave_idx_type *ierr);

  F77_RET_T
  F77_FUNC (pchim, PCHIM) (const octave_idx_type& n, const float *x, const float *f,
			   float *d, const octave_idx_type &incfd,
			   octave_idx_type *ierr);
}

// Wrapper for SLATEC/PCHIP function DPCHIM to calculate the derivates
// for piecewise polynomials.

DEFUN_DLD (__pchip_deriv__, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Loadable Function} {} __pchip_deriv__ (@var{x}, @var{y}, @var{dim})\n\
Undocumented internal function.\n\
@end deftypefn")
{
  octave_value retval;
  const int nargin = args.length ();

  bool rows = (nargin == 3 && args (2).uint_value() == 2);

  if (nargin >= 2)
    {
      if (args(0).is_single_type () || args(1).is_single_type ())
	{
	  FloatColumnVector xvec (args(0).float_vector_value ());
	  FloatMatrix ymat (args(1).float_matrix_value ());

	  octave_idx_type nx = xvec.length ();
	  octave_idx_type nyr = ymat.rows ();
	  octave_idx_type nyc = ymat.columns ();

          if (nx != (rows ? nyc : nyr))
	    {
              error ("__pchip_deriv__: dimension mismatch");
	      return retval;
	    }

          const float *yvec = ymat.data ();
	  FloatMatrix dmat (nyr, nyc);
          float *dvec = dmat.fortran_vec ();

	  octave_idx_type ierr;
          const octave_idx_type incfd = rows ? nyr : 1;
          const octave_idx_type inc = rows ? 1 : nyr;

          for (octave_idx_type i = (rows ? nyr : nyc); i > 0; i--)
	    {
              F77_FUNC (pchim, PCHIM) (nx, xvec.data (), 
                                       yvec, dvec, incfd, &ierr);

              yvec += inc;
              dvec += inc;

	      if (ierr < 0)
		{
		  error ("PCHIM error: %i\n", ierr);
		  return retval;
		}
	    }

	  retval = dmat;
	}
      else
	{
	  ColumnVector xvec (args(0).vector_value ());
	  Matrix ymat (args(1).matrix_value ());

	  octave_idx_type nx = xvec.length ();
	  octave_idx_type nyr = ymat.rows ();
	  octave_idx_type nyc = ymat.columns ();

          if (nx != (rows ? nyc : nyr))
	    {
              error ("__pchip_deriv__: dimension mismatch");
	      return retval;
	    }

          const double *yvec = ymat.data ();
	  Matrix dmat (nyr, nyc);
          double *dvec = dmat.fortran_vec ();

	  octave_idx_type ierr;
          const octave_idx_type incfd = rows ? nyr : 1;
          const octave_idx_type inc = rows ? 1 : nyr;

          for (octave_idx_type i = (rows ? nyr : nyc); i > 0; i--)
	    {
              F77_FUNC (dpchim, DPCHIM) (nx, xvec.data (), 
                                         yvec, dvec, incfd, &ierr);

              yvec += inc;
              dvec += inc;

	      if (ierr < 0)
		{
		  error ("DPCHIM error: %i\n", ierr);
		  return retval;
		}
	    }

	  retval = dmat;
	}
    }

  return retval;
}
