<?php
	# ------- The graph values in the form of associative array
	function xyz2lab($v,$x,$y,$z) {
	
	
	//116*(IF($y>0.885645,($y/100)^(1/3),7.787037*N4/100+0.137931))-16
//=500*((IF(M4>0.853957,(M4/96.422)^(1/3),(7.787037*(M4/96.422))+0.137931)-(IF(N4>0.885645,(N4/100)^(1/3),(7.787037*(N4/100))+0.137931))))	

	if ($v=="l") {
		
		if ($y>0.885645) {
			$l=116*pow(($y/100),(1/3))-16;}
		else {	
			$l=116*(7.787037*$y/100+0.137931)-16;
			}
		return $l;	
	}
	
	if ($v=="a") {
		if ($x>0.853957) {
				if ($y>0.885645) {
			$a=500*((pow(($x/96.422),1/3))-pow(($y/100),(1/3)));}
				else {
			$a=500*((pow(($x/96.422),1/3))-((7.787037*($y/100))+0.137931));}	
				}
			
		else {	
				if ($y>0.885645) {
				$a=500*((7.787037*$x/96.422)+0.137931)-pow(($y/100),(1/3));}
				else {
				$a=500*((7.787037*$x/96.422)+0.137931)-((7.787037*($y/100))+0.137931);}
			}
		return $a;
		}
//=200*((IF(N4>0.885645,(N4/100)^(1/3),(7.787037*(N4/100))+0.137931)-(IF(O4>0.730843,(O4/82.521)^(1/3),(7.787037*(O4/82.521))+0.137931))))	
//=200*((IF(N1270>0.885645,(N1270/100)^(1/3),(7.787037*(N1270/100))+0.137931)-(IF(O1270>0.730843,(O1270/82.521)^(1/3),(7.787037*(O1270/82.521))+0.137931))))	
	if ($v=="b") {
		if ($y>0.885645) {
				if ($z>0.730843) {
			$b=200*((pow(($y/100),1/3))-pow(($z/82.521),(1/3)));}
				else {
			$b=200*((pow(($y/100),1/3))-((7.787037*($z/82.521))+0.137931));}	
				}
			
		else {	
				if ($z>0.730843) {
				$b=200*(((7.787037*$y/100)+0.137931)-pow(($z/82.521),(1/3)));}
				else {
				$b=200*(((7.787037*$y/100)+0.137931)-((7.787037*($z/82.521))+0.137931));}
			}
		return $b;
		}

	

}
?>