Writing matrices in LaTeX is kind of annoying, and I personally find it easier to just make a 2d-array in a Python script and then using a script to convert that to LaTeX. To ease my suffering, I wrote a couple short Python and Haskell scripts to convert arrays to LaTeX matrices, and also to perform specified row operations on those matrices while outputting the results of each intermediate step in LaTeX.
Well, it was useful during EE16A anyway.
Continued in tex-markup.