Brown here... I dropped out of Engineering at least in part because the maths was too hard, and in CS I skipped several of the more maths-based classes and concentrated on programming, operating systems, and networks. Basically my maths never progressed a good high school level, and by 2011 it had certainly taken some steps back. I don't even consider myself to have the standard of an amateur mathematician. (It's only since I got into psychology, and hence regression, that I have learned what an eigenvalue is.)