#include <stdio.h>

#include <stdlib.h>

#include <gsl/gsl_math.h>

#include <gsl/gsl_filter.h>

#include <gsl/gsl_rng.h>

#include <gsl/gsl_randist.h>

#include <gsl/gsl_vector.h>

int

main(void)

{

  const size_t N = 1000;                               /* length of time series */

  const size_t K = 7;                                  /* window size */

  const double f = 5.0;                                /* frequency of square wave in Hz */

  gsl_filter_median_workspace *median_p = gsl_filter_median_alloc(K);

  gsl_filter_rmedian_workspace *rmedian_p = gsl_filter_rmedian_alloc(K);

  gsl_vector *t = gsl_vector_alloc(N);                 /* time */

  gsl_vector *x = gsl_vector_alloc(N);                 /* input vector */

  gsl_vector *y_median = gsl_vector_alloc(N);          /* median filtered output */

  gsl_vector *y_rmedian = gsl_vector_alloc(N);         /* recursive median filtered output */

  gsl_rng *r = gsl_rng_alloc(gsl_rng_default);

  size_t i;

  /* generate input signal */

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

    {

      double ti = (double) i / (N - 1.0);

      double tmp = sin(2.0 * M_PI * f * ti);

      double xi = (tmp >= 0.0) ? 1.0 : -1.0;

      double ei = gsl_ran_gaussian(r, 0.1);

      gsl_vector_set(t, i, ti);

      gsl_vector_set(x, i, xi + ei);

    }

  gsl_filter_median(GSL_FILTER_END_PADVALUE, x, y_median, median_p);

  gsl_filter_rmedian(GSL_FILTER_END_PADVALUE, x, y_rmedian, rmedian_p);

  /* print results */

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

    {

      double ti = gsl_vector_get(t, i);

      double xi = gsl_vector_get(x, i);

      double medi = gsl_vector_get(y_median, i);

      double rmedi = gsl_vector_get(y_rmedian, i);

      printf("%f %f %f %f\n",

             ti,

             xi,

             medi,

             rmedi);

    }

  gsl_vector_free(t);

  gsl_vector_free(x);

  gsl_vector_free(y_median);

  gsl_vector_free(y_rmedian);

  gsl_rng_free(r);

  gsl_filter_median_free(median_p);

  return 0;

}