/**
* Constructor
*
* Sets up the Graph class with an image width and height defaults to
* 640x480
*
* @param Integer $width Image width
* @param Integer $height Image height
*/
public function __construct($width = 640, $height = 480)
{
// default width and height equal to that of a poor monitor (in early 2000s)
$this->width = $width;
$this->height = $height;
//initialize main class variables
parent::__construct();
}
