Zabbix

/*

** Copyright (C) 2001-2025 Zabbix SIA

**

** This program is free software: you can redistribute it and/or modify it under the terms of

** the GNU Affero General Public License as published by the Free Software Foundation, version 3.

**

** 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 Affero General Public License for more details.

**

** You should have received a copy of the GNU Affero General Public License along with this program.

** If not, see <https://www.gnu.org/licenses/>.

**/

​

#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: calculates 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: evaluates 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;

        fourth_moment += diff * diff * diff * diff;

    }

​

    second_moment /= values->values_num;

    fourth_moment /= values->values_num;