Math Conversion

[foofoobar]

Ok this is easy and dumb, I just can't remember the math function.

How do I convert a negative number to 0?

Basically I want a calculation to always be zero if it is ever a negative number. And I know there is a math function for this, I just can't remember what and it is driving me crazy.

[Natty_Dreadlock]

what about:
if($number < 0) $number = 0; ???

[foofoobar]

Yeah, I could do that but I REALLY want to know what the math function is for that. It's driving me crazy!