[tripzilch]

I just had the Asphyxia Demotutorials (look them up on one of those oldskool textfiles websites, maybe it's exactly what you are referring to? except of course the bits were they also learn you Turbo Pascal and ASM :p) But the arithmetic, goniometry (trigonometry?) and geometry were the hard parts, which I learned in school, but were still tricky (because I liked learning, not memorizing formulas).

Linear algebra was the new and easy part. You don't need matrix inversions, eigenvectors or triangular decompositions or any of the complex Linear Algebra stuff. It's just vector math. And you probably already know arrays. It's merely a notational convenience when you recognize that you're doing the exact same operations on three x,y,z-variables all the time.

When I saw it first as a teenager I was like "hey that's clever, lots less to write!" (when working out formulas on pen and paper, not having to write everything thrice, yay!).