// f-quad.cc                                           -*- C++ -*-
/*

Copyright (C) 1993 John W. Eaton

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 2, 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, write to the Free
Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

*/

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

#include <strstream.h>

#include "Quad.h"

#include "tree-const.h"
#include "variables.h"
#include "mappers.h"
#include "gripes.h"
#include "error.h"
#include "utils.h"
#include "pager.h"
#include "f-quad.h"

// Global pointer for user defined function required by quadrature functions.
static tree *quad_fcn;

#ifdef WITH_DLD
tree_constant *
builtin_quad_2 (const tree_constant *args, int nargin, int nargout)
{
  return do_quad (args, nargin, nargout);
}

tree_constant *
builtin_quad_options_2 (const tree_constant *args, int nargin, int nargout)
{
  return quad_options (args, nargin, nargout);
}
#endif

static Quad_options quad_opts;

double
quad_user_function (double x)
{
  double retval = 0.0;

//  tree_constant name = tree_constant (quad_fcn->name ());
  tree_constant *args = new tree_constant [2];
//  args[0] = name;
  args[1] = tree_constant (x);

  if (quad_fcn != NULL_TREE)
    {
      tree_constant *tmp = quad_fcn->eval (args, 2, 1, 0);

      delete [] args;

      if (error_state)
	{
	  delete [] tmp;
	  quad_integration_error = 1;  // XXX FIXME XXX
	  gripe_user_supplied_eval ("quad");
	  return retval;
	}

      if (tmp != NULL_TREE_CONST && tmp[0].is_defined ())
	{
	  retval = tmp[0].to_scalar ();
	  delete [] tmp;
	}
      else
	{
	  delete [] tmp;
	  quad_integration_error = 1;  // XXX FIXME XXX
	  gripe_user_supplied_eval ("quad");
	}
    }

  return retval;
}

tree_constant *
do_quad (const tree_constant *args, int nargin, int nargout)
{
// Assumes that we have been given the correct number of arguments.

  tree_constant *retval = NULL_TREE_CONST;

  quad_fcn = is_valid_function (args[1], "fsolve", 1);
  if (quad_fcn == NULL_TREE
      || takes_correct_nargs (quad_fcn, 2, "fsolve", 1) != 1)
    return retval;

  double a = args[2].to_scalar ();
  double b = args[3].to_scalar ();

  int indefinite = 0;
  IndefQuad::IntegralType indef_type = IndefQuad::doubly_infinite;
  double bound = 0.0;
  if ((int) xisinf (a) && (int) xisinf (b))
    {
      indefinite = 1;
      indef_type = IndefQuad::doubly_infinite;
    }
  else if ((int) xisinf (a))
    {
      indefinite = 1;
      bound = b;
      indef_type = IndefQuad::neg_inf_to_bound;
    }
  else if ((int) xisinf (b))
    {
      indefinite = 1;
      bound = a;
      indef_type = IndefQuad::bound_to_inf;
    }

  int ier = 0;
  int nfun = 0;
  double abserr = 0.0;
  double val = 0.0;
  double abstol = 1e-6;
  double reltol = 1e-6;
  Vector tol (2);
  Vector sing;
  int have_sing = 0;
  switch (nargin)
    {
    case 6:
      if (indefinite)
	{
	  error("quad: singularities not allowed on infinite intervals");
	  return retval;
	}
      have_sing = 1;
      sing = args[5].to_vector ();
    case 5:
      tol = args[4].to_vector ();
      switch (tol.capacity ())
	{
	case 2:
	  reltol = tol.elem (1);
	case 1:
	  abstol = tol.elem (0);
	  break;
	default:
	  error ("quad: expecting tol to contain no more than two values");
	  return retval;
	}
    case 4:
      if (indefinite)
	{
	  IndefQuad iq (quad_user_function, bound, indef_type, abstol, reltol);
	  iq.copy (quad_opts);
	  val = iq.integrate (ier, nfun, abserr);
	}
      else
	{
	  if (have_sing)
	    {
	      DefQuad dq (quad_user_function, a, b, sing, abstol, reltol);
	      dq.copy (quad_opts);
	      val = dq.integrate (ier, nfun, abserr);
	    }
	  else
	    {
	      DefQuad dq (quad_user_function, a, b, abstol, reltol);
	      dq.copy (quad_opts);
	      val = dq.integrate (ier, nfun, abserr);
	    }
	}
      break;
    default:
      panic_impossible ();
      break;
    }

  retval = new tree_constant [5];

  retval[0] = tree_constant (val);
  retval[1] = tree_constant ((double) ier);
  retval[2] = tree_constant ((double) nfun);
  retval[3] = tree_constant (abserr);

  return retval;
}

typedef void (Quad_options::*d_set_opt_mf) (double);
typedef double (Quad_options::*d_get_opt_mf) (void);

#define MAX_TOKENS 2

struct QUAD_OPTIONS
{
  char *keyword;
  char *kw_tok[MAX_TOKENS + 1];
  int min_len[MAX_TOKENS + 1];
  int min_toks_to_match;
  d_set_opt_mf d_set_fcn;
  d_get_opt_mf d_get_fcn;
};

static QUAD_OPTIONS quad_option_table[] =
{
  { "absolute tolerance",
    { "absolute", "tolerance", NULL, },
    { 1, 0, 0, }, 1,
    Quad_options::set_absolute_tolerance,
    Quad_options::absolute_tolerance, },

  { "relative tolerance",
    { "relative", "tolerance", NULL, },
    { 1, 0, 0, }, 1,
    Quad_options::set_relative_tolerance,
    Quad_options::relative_tolerance, },

  { NULL,
    { NULL, NULL, NULL, },
    { 0, 0, 0, }, 0,
    NULL, NULL, },
};

static void
print_quad_option_list (void)
{
  ostrstream output_buf;

  print_usage ("quad_options", 1);

  output_buf << "\n"
	     << "Options for quad include:\n\n"
	     << "  keyword                                  value\n"
	     << "  -------                                  -----\n\n";

  QUAD_OPTIONS *list = quad_option_table;

  char *keyword;
  while ((keyword = list->keyword) != (char *) NULL)
    {
      output_buf.form ("  %-40s ", keyword);

      double val = (quad_opts.*list->d_get_fcn) ();
      if (val < 0.0)
	output_buf << "computed automatically";
      else
	output_buf << val;

      output_buf << "\n";
      list++;
    }

  output_buf << "\n" << ends;
  maybe_page_output (output_buf);
}

static void
do_quad_option (char *keyword, double val)
{
  QUAD_OPTIONS *list = quad_option_table;

  while (list->keyword != (char *) NULL)
    {
      if (keyword_almost_match (list->kw_tok, list->min_len, keyword,
				list->min_toks_to_match, MAX_TOKENS))
	{
	  (quad_opts.*list->d_set_fcn) (val);

	  return;
	}
      list++;
    }

  warning ("quad_options: no match for `%s'", keyword);
}

tree_constant *
quad_options (const tree_constant *args, int nargin, int nargout)
{
  tree_constant *retval = NULL_TREE_CONST;

  if (nargin == 1)
    {
      print_quad_option_list ();
    }
  else if (nargin == 3)
    {
      if (args[1].is_string_type ())
	{
	  char *keyword = args[1].string_value ();
	  double val = args[2].double_value ();
	  do_quad_option (keyword, val);
	}
      else
	print_usage ("quad_options");
    }
  else
    {
      print_usage ("quad_options");
    }

  return retval;
}

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