/* filter/median.c

 *

 * Contains routines related to the standard median filter

 * 

 * Copyright (C) 2018 Patrick Alken

 * 

 * 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_math.h>

#include <gsl/gsl_vector.h>

#include <gsl/gsl_filter.h>

#include <gsl/gsl_errno.h>

gsl_filter_median_workspace *

gsl_filter_median_alloc(const size_t K)

{

  gsl_filter_median_workspace *w;

  size_t H = K / 2;

  w = calloc(1, sizeof(gsl_filter_median_workspace));

  if (w == 0)

    {

      GSL_ERROR_NULL ("failed to allocate space for workspace", GSL_ENOMEM);

    }

  w->movstat_workspace_p = gsl_movstat_alloc(2*H + 1);

  if (w->movstat_workspace_p == NULL)

    {

      gsl_filter_median_free(w);

      GSL_ERROR_NULL ("failed to allocate space for movstat workspace", GSL_ENOMEM);

    }

  return w;

}

void

gsl_filter_median_free(gsl_filter_median_workspace * w)

{

  if (w->movstat_workspace_p)

    gsl_movstat_free(w->movstat_workspace_p);

  free(w);

}

/*

gsl_filter_median()

  Standard median filter

Inputs: endtype - end point handling

        x       - input vector

        y       - output vector

        w       - workspace

*/

int

gsl_filter_median(const gsl_filter_end_t endtype, const gsl_vector * x, gsl_vector * y, gsl_filter_median_workspace * w)

{

  int status = gsl_movstat_median(endtype, x, y, w->movstat_workspace_p);

  return status;

}