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101 lines
2.1 KiB
101 lines
2.1 KiB
1 year ago
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<?php declare(strict_types = 0);
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/*
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** Zabbix
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** Copyright (C) 2001-2023 Zabbix SIA
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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**/
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/**
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* A math helper class.
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*/
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class CMathHelper {
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/**
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* Calculate sum of values (overflow safe).
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*
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* @param array $values
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*
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* @return float
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*/
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public static function safeSum(array $values): float {
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sort($values, SORT_NUMERIC);
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$result = $values[0];
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$head = 1;
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$tail = count($values) - 1;
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while ($head <= $tail) {
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$result += $values[$result > 0 ? $head++ : $tail--];
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}
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return $result;
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}
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/**
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* Calculate multiplication of values (overflow safe).
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*
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* @param array $values
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*
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* @return float
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*/
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public static function safeMul(array $values): float {
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usort($values, function(float $a, float $b): int {
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return abs($a) <=> abs($b);
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});
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$result = $values[0];
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$head = 1;
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$tail = count($values) - 1;
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while ($head <= $tail) {
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$result *= $values[abs($result) > 1 ? $head++ : $tail--];
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}
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return $result;
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}
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/**
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* Calculate average of values (overflow safe).
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*
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* @param array $values A non-empty array of values.
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*
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* @return float
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*/
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public static function safeAvg(array $values): float {
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sort($values, SORT_NUMERIC);
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$result = 0;
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$count = 1;
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$head = 0;
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$tail = count($values) - 1;
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while ($head <= $tail) {
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$value = $values[$result > 0 ? $head++ : $tail--];
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// Expression optimized to avoid overflow.
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$result += $value / $count - $result / $count;
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$count++;
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}
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return $result;
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}
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}
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