Generates factorial's

factorials.php

<?php

$time_start = microtime(true);
$iterations = 20;

header('Content-Type: text/plain');

function convert($size)
 {
    $unit=array('b','kb','mb','gb','tb','pb');
    return @round($size/pow(1024,($i=floor(log($size,1024)))),2).' '.$unit[$i];
 }

function factorial( $n )
{
  return accumulate( 1, $n );
}

function accumulate( $current, $n )
{
  return $n == 0 ? $current : accumulate( $current * $n, $n - 1);
}

echo "Generating Factorals up to $iterations \n";

for ( $i = 1; $i <= $iterations; $i++ )
{
    echo str_pad ( $i, 4 , ' ' ) . factorial( $i ) . "\n";
}

$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Completed in $time seconds using ". convert(memory_get_usage(true)) . " memory\n";