public static arrayCantBeEmpty ( ) : |
||
return |
/** * @param array|float[] $a * @param bool $sample * * @return float * * @throws InvalidArgumentException */ public static function population(array $a, $sample = true) { if (empty($a)) { throw InvalidArgumentException::arrayCantBeEmpty(); } $n = count($a); if ($sample && $n === 1) { throw InvalidArgumentException::arraySizeToSmall(2); } $mean = Mean::arithmetic($a); $carry = 0.0; foreach ($a as $val) { $d = $val - $mean; $carry += $d * $d; } if ($sample) { --$n; } return sqrt((double) ($carry / $n)); }
/** * @param array $array * * @throws InvalidArgumentException */ private static function checkArrayLength(array $array) { if (0 == count($array)) { throw InvalidArgumentException::arrayCantBeEmpty(); } }