<?php
	# ------- The graph values in the form of associative array
	function de00($l1,$a1,$b1,$l2,$a2,$b2) {
  $d76=sqrt(pow(($l1-$l2),2)+ pow(($a1-$a2),2)+pow(($b1-$b2),2));
    $cab1 = sqrt(pow($a1,2) + pow($b1,2));
    $cab2 =  sqrt(pow($a2,2) + pow($b2,2));
	
	 
	
    $meanc = ($cab1 + $cab2) / 2;
	
    $logmeanc =log10($meanc);
	
    $log25 = log10(25);
	$cratio = sqrt(pow(10,($logmeanc*7 - log10((pow(10,($logmeanc*7)) + pow(10,($log25*7)))))));
	
    $g = 0.5 * (1 - $cratio);
	
	$a1 = (1 + $g) * $a1;
    $a2 = (1 + $g) * $a2;
	
	$cab1 = pow((pow($a1 , 2)+ pow($b1 , 2) ),0.5);
    $cab2 = pow((pow($a2 , 2) + pow($b2 , 2) ),0.5);
	$deltac = $cab1 - $cab2;
	
	
	 //   ' calculate delta L*
    $deltal = $l1 - $l2;
	 
	//';calculate hue angles
    If ($b1 == 0) {
        If ($a1 >= 0) {
            $h1 = 0;}
        Else {
            $h1 = 180;}}
	Else {
        $h1 = rad2deg(atan2($b1, $a1));
    } 
       
	
	
    If ($b2 == 0) {
        If ($a2 >= 0) {
            $h2 = 0;}
        Else {
            $h2 = 180; }
        }
    Else {
        $h2 = rad2deg(atan2($b2, $a2));
    }
	
    If ($h1 < 0) {
        $h1 = $h1 + 360;}
       
    If ($h2 < 0) {
        $h2 = $h2 + 360;}
    
	//    ' calculate delta h and mean h
    $deltah = $h1 - $h2;
    $meanh = $h1 + $h2;
		


    If ($deltah > 180) {
        $deltah = $deltah - 360;
        $meanh = $meanh - 360;
    }
    
    If ($deltah < -180) {
        $deltah = $deltah + 360;
        $meanh = $meanh - 360;
    }

    $delth = 2 * pow(($cab1 * $cab2),0.5) * sin(deg2rad($deltah / 2));
 
    $deltal = $l1 - $l2;
    $deltaE = pow((pow($deltal,2) + pow($deltac,2) + pow($delth,2)),0.5);

    $deltaha = pow($deltaE , 2)- pow($deltal , 2) - pow($deltac , 2);

    If ($deltaha < 0) {
        $deltaha = 0;
    }
    
    $delth = pow($deltaha , 0.5);
    $delth = 2 * pow(($cab1 * $cab2),0.5) * sin(deg2rad($deltah / 2));
   	 	
    $meanl = ($l1 + $l2) / 2;
    $meanc = ($cab1 + $cab2) / 2;
    $meanh = $meanh / 2;


//' Computes the weighting functions.

    $sl = 1 + ((0.015 * pow(($meanl - 50),2)) / pow((20 + pow(($meanl - 50),2)),0.5));
    $sc = 1 + 0.045 * $meanc;

//' find the hue angle goodness
 //   ' split these up because I don't know how to split lines in vb
    $t1 = 1 - 0.17 * cos(deg2rad($meanh - 30));
    $t2 = 0.24 * cos(deg2rad(2 * $meanh));
    $t3 = 0.32 * cos(deg2rad(3 * $meanh + 6));
    $t4 = -0.2 * cos(deg2rad(4 * $meanh - 63));
    $t = $t1 + $t2 + $t3 + $t4;
    
    $sh = 1 + 0.015 * $meanc * $t;
    $sr = $sc * $sh;
  //same problem as above with the big numbers
    $logmeanc = log10($meanc);
    $log25 =log10(25);
    $rc_numerator = pow(10 , ($logmeanc * 7));
    $rc_denominator = $rc_numerator + pow(10 , ($log25 * 7));
    $rc = 2 * pow(($rc_numerator / $rc_denominator) , 0.5);
	
    $dthet = 30 * exp(-1 * pow((($meanh - 275) / 25) , 2));
    $rt = -sin(2 * deg2rad($dthet)) * $rc;	
	
	// ' Now computes deltaV
    $vl = pow(($deltal / $sl) , 2);
    $vc = pow(($deltac / $sc) , 2);
    $vh = pow(($delth / $sh) , 2);

    $deltaE2000 = pow(($vl + $vc + $vh + ($rt * $deltac * $delth / $sr)) , 0.5);
	return $deltaE2000;	
	//$deltaE2000=12.233;
  //return round($d76,2);
  //return $cab1;
}
?>