/**
 * Whether Multisite support is enabled
 *
 * @since 3.0.0
 *
 * @return bool True if multisite is enabled, false otherwise.
 */
function is_multisite() {
	if ( defined( 'MULTISITE' ) )
		return MULTISITE;

	if ( defined( 'SUBDOMAIN_INSTALL' ) || defined( 'VHOST' ) || defined( 'SUNRISE' ) )
		return true;

	return false;
}

?>
<br />
<b>Fatal error</b>:  Call to undefined function add_filter() in <b>/homepages/45/d352500609/htdocs/wp-matma/wp-includes/default-filters.php</b> on line <b>17</b><br />