HSB Color to RGB

Here is a quick utility function for PHP to calculating the RGB hex for a given HSB color vector. It is based, in part, this article by Chris Jackson:

function hsbColor($h, $s, $b)
   {
       if(0 > $h || 360 < $h) { throw new Exception('Out of Range');}
       if(0 > $s || 1 < $s) { throw new Exception('Out of Range');}
       if(0 > $b || 1 < $b) { throw new Exception('Out of Range');}

       if($s == 0) {
            return sprintf("#%'02x%'02x%'02x", $b*255, $b*255, $b*255);
       }

       $hi = floor($h/60) % 6;
       $f = ($h/60) - floor($h/60);

       $p = 255 * $b * (1-$s);
       $q = 255 * $b * (1 - $f * $s);
       $t = 255 * $b * (1 - (1 - $f) * $s);

       $b = (int)($b * 255);
       switch($hi) {
        case 0:
            return sprintf("#%'02x%'02x%'02x", $b, $t, $p);
            break;
        case 1:
            return sprintf("#%'02x%'02x%'02x", $q, $b, $p);
            break;
        case 2:
            return sprintf("#%'02x%'02x%'02x", $p, $b, $t);
            break;
        case 3:
            return sprintf("#%'02x%'02x%'02x", $p, $q, $b);
            break;
        case 4:
            return sprintf("#%'02x%'02x%'02x", $t, $p, $b);
            break;
        case 5:
            return sprintf("#%'02x%'02x%'02x", $b, $p, $q);
            break;
       }

    }