SMARTY_DIR

This should be the full system path to the location of the Smarty class files. If this is not defined, then Smarty will attempt to determine the appropriate value automatically. If defined, the path must end with a slash.

// set path to Smarty directory
define("SMARTY_DIR","/usr/local/lib/php/Smarty/");

require_once(SMARTY_DIR."Smarty.class.php");