Hi, I just profiled my program using gprof, and found out that it spends as much as 60% of it's time in a function which returns a pseudo random number. Now I'm looking for something a lot faster than the regular rand()-approach. I found out about the Mersenne Twister algorithm, which supposedly is a great deal faster than the libc-functions. The main problem is that I don't have a clue on how to make it return a random integer between X and Y, which is crucial for my program. I'd like to be able to do GetRandomNumber(3, 15); to get a pseudo random number between 3 and 15, for example.

The Mersenne Twister is available here:
http://www.math.keio.ac.jp/matumoto/...02/mt19937ar.c

I'd be really grateful for any help possible, because it's a real pain watching 60% of your programs execution time being wasted on random numbers, when it does lots and lots of more important operations in between. Thank you.

Without even looking at the algorithm, if you have an integer and you mod it by (Y-X) and add X to it then you will always get a number between X and Y.

Something like this would do
rnum = (rnum % (y-x))+x;

Don't know if it's faster, but try using the kernel random generator.
You could make a function that reads random bytes from /dev/urandom (these bytes are provided by the kernel) and use jtshaw's method to get a number within a range from it.