I have a data set (ie a = f(x,y,z)). I'm trying apply a regression to it, but all I can seem to find are articles fitting z = f(x,y). Could someone please point me at a relevant article, I believe I'm having difficulties because of my incorrect regression vernacular. Any suggestions are appreciated.
This is typically known as either "multiple regression" or "multivariate regression". That should help you find resources online. You can use the regress() function to do it in MATLAB.
Is it a polynomial you're looking for? If so - write out the equations and then put them in matrix form and solve them using ax=b. We can help more if you give us significantly more information.