I am trying to figure out how to work with a 4x4 matrix, in particular rotating them. I have been searching and reading differnt things but I keep hitting a brick wall when I see the formulas. I can see which parts of the matrix need to be changed depending on if I rotate on the x, y or z axis. But I cannot interpet their formulas so as to use them in code.

I have tried several experiments and I am not geting the right numbers. And since they use letters and greek letters and give no point of refernce for them I am sure additional calculation are need but there is no clear reference to the correct calculation. In one fomula I saw they used cosine and sine with the theta character in parenthases which previously in the article it was defined as pi/2 (which makes no sense at all) but that didn't work when I used it.

I am hoping someone has some nice clearly defined formulas I can work with.