3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = array(9,4,-3,-10); function stddev($array){ //Don Knuth is the $deity of algorithms //http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#III._On-line_algorithm $n = 0; $mean = 0; $M2 = 0; foreach($array as $x){ $n++; $delta = $x - $mean; $mean = $mean + $delta/$n; $M2 = $M2 + $delta*($x - $mean); } $variance = $M2/($n - 1); return sqrt($variance); } stddev($array); ?>
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
preferences:
296.84 ms | 406 KiB | 357 Q