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/* movstat/snacc.c
*
* Moving window S_n accumulator
*
* 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 <gsl/gsl_math.h>
#include <gsl/gsl_vector.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_movstat.h>
#include <gsl/gsl_sort.h>
#include <gsl/gsl_statistics.h>
typedef double snacc_type_t;
typedef snacc_type_t ringbuf_type_t;
#include "ringbuf.c"
typedef struct
{
snacc_type_t *window; /* linear array for current window */
snacc_type_t *work; /* workspace */
ringbuf *rbuf; /* ring buffer storing current window */
} snacc_state_t;
static size_t
snacc_size(const size_t n)
{
size_t size = 0;
size += sizeof(snacc_state_t);
size += 2 * n * sizeof(snacc_type_t);
size += ringbuf_size(n);
return size;
}
static int
snacc_init(const size_t n, void * vstate)
{
snacc_state_t * state = (snacc_state_t *) vstate;
state->window = (snacc_type_t *) ((unsigned char *) vstate + sizeof(snacc_state_t));
state->work = (snacc_type_t *) ((unsigned char *) state->window + n * sizeof(snacc_type_t));
state->rbuf = (ringbuf *) ((unsigned char *) state->work + n * sizeof(snacc_type_t));
ringbuf_init(n, state->rbuf);
return GSL_SUCCESS;
}
static int
snacc_insert(const snacc_type_t x, void * vstate)
{
snacc_state_t * state = (snacc_state_t *) vstate;
/* add new element to ring buffer */
ringbuf_insert(x, state->rbuf);
return GSL_SUCCESS;
}
static int
snacc_delete(void * vstate)
{
snacc_state_t * state = (snacc_state_t *) vstate;
if (!ringbuf_is_empty(state->rbuf))
ringbuf_pop_back(state->rbuf);
return GSL_SUCCESS;
}
/* FIXME XXX: this is inefficient - could be improved by maintaining a sorted ring buffer */
static int
snacc_get(void * params, snacc_type_t * result, const void * vstate)
{
const snacc_state_t * state = (const snacc_state_t *) vstate;
size_t n = ringbuf_copy(state->window, state->rbuf);
(void) params;
gsl_sort(state->window, 1, n);
*result = gsl_stats_Sn_from_sorted_data(state->window, 1, n, state->work);
return GSL_SUCCESS;
}
static const gsl_movstat_accum sn_accum_type =
{
snacc_size,
snacc_init,
snacc_insert,
snacc_delete,
snacc_get
};
const gsl_movstat_accum *gsl_movstat_accum_Sn = &sn_accum_type;
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