simple function helps calculate resized dimensions while keeping w/h aspect ratio

calc_aspect_ratio

<?php
function calc_aspect_ratio($w=0,$h=0,$image_dimensions=array()){
	//work out some ratios for the resized dimensions
	if($w){
		$w_ratio=$w/$image_dimensions[0];
	} else {
		$w_ratio=1;
	}
	if($h){
		$h_ratio=$h/$image_dimensions[1];
	}else{
		$h_ratio=1;
	}
	if($w_ratio<=$h_ratio){
		$w=round($image_dimensions[0]*$w_ratio);
		$h=round($image_dimensions[1]*$w_ratio);
	}else{
		$w=round($image_dimensions[0]*$h_ratio);
		$h=round($image_dimensions[1]*$h_ratio);
	}
	return array('w'=>$w, 'h'=>$h);
}
?>