/* histogram/test2d_resample.c

 * 

 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough

 * 

 * This program 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.

 * 

 * This program 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 program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 */

#include <config.h>

#include <stdlib.h>

#include <math.h>

#include <gsl/gsl_histogram2d.h>

#include <gsl/gsl_test.h>

#include <gsl/gsl_ieee_utils.h>

#include "urand.c"

void

test2d_resample (void)

{

  size_t i, j;

  int status = 0;

  double total = 0;

  size_t N = 200000;

  gsl_histogram2d *h;

  gsl_ieee_env_setup ();

  h = gsl_histogram2d_calloc_uniform (10, 10, 0.0, 1.0, 0.0, 1.0);

  for (i = 0; i < 10; i++)

    {

      for (j = 0; j < 10; j++)

        {

          double w = 10.0 * i + j;

          total += w;

          gsl_histogram2d_accumulate (h, 0.1 * i, 0.1 * i, w);

        }

    }

  {

    gsl_histogram2d_pdf *p = gsl_histogram2d_pdf_alloc (10,10);

    gsl_histogram2d *hh = gsl_histogram2d_calloc_uniform (20, 20,

                                                          0.0, 1.0,

                                                          0.0, 1.0);

    gsl_histogram2d_pdf_init (p, h);

    for (i = 0; i < N; i++)

      {

        double u = urand();

        double v = urand();

        double x, y;

        status = gsl_histogram2d_pdf_sample (p, u, v, &x, &y);

        status = gsl_histogram2d_increment (hh, x, y);

      }

    status = 0;

    for (i = 0; i < 20; i++)

      {

        for (j = 0; j < 20; j++)

          {

            double z = 4 * total * gsl_histogram2d_get (hh, i, j) / (double) N;

            size_t k1, k2;

            double ya;

            double x, xmax, y, ymax;

            gsl_histogram2d_get_xrange (hh, i, &x, &xmax;;

            gsl_histogram2d_get_yrange (hh, j, &y, &ymax);

            gsl_histogram2d_find (h, x, y, &k1, &k2;;

            ya = gsl_histogram2d_get (h, k1, k2);

            if (ya == 0)

              {

                if (z != 0)

                  {

                    status = 1;

                    printf ("(%d,%d): %g vs %g\n", (int)i, (int)j, z, ya);

                  }

              }

            else

              {

                double err = 1 / sqrt (gsl_histogram2d_get (hh, i, j));

                double sigma = fabs ((z - ya) / (ya * err));

                if (sigma > 3)

                  {

                    status = 1;

                    printf ("%g vs %g err=%g sigma=%g\n", z, ya, err, sigma);

                  }

              }

          }

      }

    gsl_histogram2d_pdf_free (p) ;

    gsl_histogram2d_free (hh) ;

    gsl_test (status, "gsl_histogram2d_pdf_sample within statistical errors");

  }

  gsl_histogram2d_free (h) ;

}