/* histogram/test1d_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_histogram.h>

#include <gsl/gsl_test.h>

#include <gsl/gsl_ieee_utils.h>

#include "urand.c"

void

test1d_resample (void)

{

  size_t i;

  int status = 0;

  gsl_histogram *h;

  gsl_ieee_env_setup ();

  h = gsl_histogram_calloc_uniform (10, 0.0, 1.0);

  gsl_histogram_increment (h, 0.1);

  gsl_histogram_increment (h, 0.2);

  gsl_histogram_increment (h, 0.2);

  gsl_histogram_increment (h, 0.3);

  {

    gsl_histogram_pdf *p = gsl_histogram_pdf_alloc (10);

    gsl_histogram *hh = gsl_histogram_calloc_uniform (100, 0.0, 1.0);

    gsl_histogram_pdf_init (p, h);

    for (i = 0; i < 100000; i++)

      {

        double u = urand();

        double x = gsl_histogram_pdf_sample (p, u);

        gsl_histogram_increment (hh, x);

      }

    for (i = 0; i < 100; i++)

      {

        double y = gsl_histogram_get (hh, i) / 2500;

        double x, xmax;

        size_t k;

        double ya;

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

        gsl_histogram_find (h, x, &k);

        ya = gsl_histogram_get (h, k);

        if (ya == 0)

          {

            if (y != 0)

              {

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

                status = 1;

              }

          }

        else

          {

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

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

            if (sigma > 3)

              {

                status = 1;

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

              }

          }

      }

    gsl_histogram_pdf_free (p) ;

    gsl_histogram_free (hh);

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

  }

  gsl_histogram_free (h);

}