<?php

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

function resize($w2, $h2 = null)
{
	$w1 = 100;
	$h1 = 50;
	
	if ( $h2 === null )
	{
		$h2 = $h1 / ($w1 / $w2);
		return 'Computed height is ' . round($h2);
	}
	else
	{
		return;
	}
}

echo resize(200);

?>