I am trying to output xml by using domxml\_new\_doc. 

However, I just got the call to undefined function domxml\_new\_doc() error.
I tried google it but still not luck. Do I have to install any extension or 
library? Thanks for the help.

```
 $doc=domxml_new_doc("1.0"); //error on this line....
$node=$doc->create_element("marker");
$parnode=$doc->append_child($node);

```