Phpml\Math\Statistic\StandardDeviation::population()

Complexity

Conditions	6
Paths	6

Size

Total Lines	22
Code Lines	12

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
    public static function population(array $numbers, bool $sample = true): float
    {
        $n = count($numbers);
        if ($n === 0) {
            throw new InvalidArgumentException('The array has zero elements');
        }

        if ($sample && $n === 1) {
            throw new InvalidArgumentException('The array must have at least 2 elements');
        }

        $mean = Mean::arithmetic($numbers);
        $carry = 0.0;
        foreach ($numbers as $val) {
            $carry += ($val - $mean) ** 2;
        }

        if ($sample) {
            --$n;
        }

        return ($carry / $n) ** .5;
    }