Hello all, I've been looking at a piece of puedo code here:- http://freespace.virgin.net/hugo.elias/graphics/x_polygo.htm I've never come across a frac function before in the maths.h, what is it and what's the C equivilant? Thanks in advance.

It returns the fractional part of the argument. Ie frac(3.14) will return 0.14. You can emulate it by something like

float frac(float f) {
int i = (int)f;
return f - i;
}

Of course this won't work for very large numbers, but for should for the purpose of the article.

Note that it's usually easier and faster to work with fixed-point math for the things mentioned in the article (in which case the frac() operation can be as simple as a single bitwise AND operation).

Thanks for that :)