looks at possibilties; what functions should I study? I'm going to start work on a PHP project that will involve me doing work on numerical possibilities/probabilities, things of this nature. I'm wondering what functions I should look at and study.

The kinds of things I'll want to do are things like generating a list of 8 variables, and all the possible combinations/orders they could go in if any of the 8 variables could be placed in any order. I might then apply rules to those variables, so I know in those cases, I probably want to be looking at the str* variables.

Any ideas on the types of functions I might look at for generating an array of all possible combinations of distributions for many variables into slots?
Also, FWIW, I should explain that I'm not interested in random generation as much as comprehensive generation of possibilities. So I'm not as concerned with randomness as I am with functions that will allow me to create thorough maps of all possibilities. For instance, imagine I had

A, B, C, D, E, F, G, H

and could place them in any order. I would want to generate an array of all possibilities, and then filter by rules and see how each rule impacts the number of possibilities.

It's a school project I'm working on.

A quick search of "probability php" on Google brought this up:
http://www-128.ibm.com/developerwork...ary/wa-probab/