/**

 * @file stats.c

 * @note Copyright (C) 2013 Miroslav Lichvar <mlichvar@redhat.com>

 *

 * 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 2 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 <math.h>

#include <string.h>

#include <stdlib.h>

#include "stats.h"

struct stats {

	unsigned int num;

	double min;

	double max;

	double mean;

	double sum_sqr;

	double sum_diff_sqr;

};

struct stats *stats_create(void)

{

	struct stats *stats;

	stats = calloc(1, sizeof *stats);

	return stats;

}

void stats_destroy(struct stats *stats)

{

	free(stats);

}

void stats_add_value(struct stats *stats, double value)

{

	double old_mean = stats->mean;

	if (!stats->num || stats->max < value)

		stats->max = value;

	if (!stats->num || stats->min > value)

		stats->min = value;

	stats->num++;

	stats->mean = old_mean + (value - old_mean) / stats->num;

	stats->sum_sqr += value * value;

	stats->sum_diff_sqr += (value - old_mean) * (value - stats->mean);

}

unsigned int stats_get_num_values(struct stats *stats)

{

	return stats->num;

}

int stats_get_result(struct stats *stats, struct stats_result *result)

{

	if (!stats->num)

		return -1;

	result->min = stats->min;

	result->max = stats->max;

	result->max_abs = stats->max > -stats->min ? stats->max : -stats->min;

	result->mean = stats->mean;

	result->rms = sqrt(stats->sum_sqr / stats->num);

	result->stddev = sqrt(stats->sum_diff_sqr / stats->num);

	return 0;

}

void stats_reset(struct stats *stats)

{

	memset(stats, 0, sizeof *stats);

}