Parsing LaTeX, where to put the code

[RVSmarter]

Hello,

I am trying to add Latex to my math forum. I need to call the code below so that when people post with [tex] [/tex] it will render mathmatical equations.

include_once('/full_path_here_to/latexrender/latex.php');
$latextext=latex_content($latextext);

I just don't know in what php file or where to place the code.

Any help would be greatly appreciated.

Thanks