add_event_handler('loc_end_page_header', 'My_analytics_tag');
function My_analytics_tag(){

$My_Tag =" <!-- Matomo --><script>
var _paq = window._paq = window._paq || [];
_paq.push(['setVisitorCookieTimeout', 34186669]);
_paq.push(['setSessionCookieTimeout', 1800]);
_paq.push(['setReferralCookieTimeout', 15778463]);
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
_paq.push(['alwaysUseSendBeacon']);
_paq.push(['setTrackerUrl', \""]);
_paq.push(['setSiteId', '1']);
var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
g.type='text/javascript';
 g.async=true;
 g.src=\"";
 s.parentNode.insertBefore(g,s);
</script>
<!-- End Matomo Code --> ";

global $template;
$template->append('head_elements', $My_Tag );
}