Variables inside functions

[wavesurf]

How do you get functions on a page to work inside a function?

I have a file which includes a header file. This header file in turn includes a variables.php-file and functions.php-file. One variable is set inside the variables.php-file, and I need this to work inside a function inside the functions.php-file.

I have a sneaking suspicion that this is a really stupid question, but anyhow. Anyone have any ideas?

[jatar_k]

as ergophobe says
scope [php.net], it's not just a mouthwash anymore :)