Zabbix

/*

** Zabbix

** Copyright (C) 2001-2023 Zabbix SIA

**

** 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 "zbxeval.h"

​

#include "zbxnum.h"

#include "zbxalgo.h"

​

typedef struct

{

    double  upper;

    double  count;

}

zbx_histogram_t;

ZBX_VECTOR_DECL(histogram, zbx_histogram_t)

ZBX_VECTOR_IMPL(histogram, zbx_histogram_t)

​

static int  zbx_is_normal_double(double dbl)

{

    if (FP_ZERO != fpclassify(dbl) && FP_NORMAL != fpclassify(dbl))

        return FAIL;

​

    return SUCCEED;

}

​

/******************************************************************************

 *                                                                            *

 * Purpose: calculate arithmetic mean (i.e. average)                          *

 *                                                                            *

 * Parameters: v - [IN] non-empty vector with input data                      *

 *                                                                            *

 * Return value: arithmetic mean value                                        *

 *                                                                            *

 ******************************************************************************/

static double   calc_arithmetic_mean(const zbx_vector_dbl_t *v)

{

    double  sum = 0;

    int i;

​

    for (i = 0; i < v->values_num; i++)

        sum += v->values[i];

​

    return sum / v->values_num;

}

​

/******************************************************************************

 *                                                                            *

 * Purpose: evaluate function 'kurtosis'                                      *

 *                                                                            *

 * Parameters: values - [IN] non-empty vector with input data                 *

 *             result - [OUT] calculated value                                *

 *             error  - [OUT] dynamically allocated error message             *

 *                                                                            *

 * Return value: SUCCEED - evaluated successfully                             *

 *               FAIL - failed to evaluate function (see 'error')             *

 *                                                                            *

 ******************************************************************************/

int zbx_eval_calc_kurtosis(zbx_vector_dbl_t *values, double *result, char **error)

{

    double  mean, second_moment = 0, fourth_moment = 0, second_moment2, res;

    int i;

​

    /* step 1: calculate arithmetic mean */

    mean = calc_arithmetic_mean(values);

​

    if (SUCCEED != zbx_is_normal_double(mean))

        goto err;

​

    /* step 2: calculate the second and the fourth moments */

​

    for (i = 0; i < values->values_num; i++)

    {

        double  diff = values->values[i] - mean;

​

        second_moment += diff * diff;