User-defined function library?

Hi. I hope this is a quick and easy question for you guys. I'm trying to include() a php that just has function declarations. I hoped that could be a common resource for all my pages on the site. When I try to use the functions, however, it doesn't recognize them. Is there a way to make my own library or just include them properly? I'm open to suggestions. Thanks

should be fine as long as the functions are included prior to the include call - and as long as the include is a php page and the contents surrounded by <?php ?> tags.

any class of functions would be used similarly - included and then called

func.php
<?php
function &doublit($arg)
{
$res = $arg*2;
return $res;
}
?>

call.php
include('func.php');
$blat = &doublit(12);
echo $blat;