I'll leave the discussion of how embellished this post/blog/exercise of MIT Comp Sci in 1 year is to other comments.
But! The explanation of Fourier transforms from Scott's notes (http://www.scotthyoung.com/mit/fourier.pdf) is one of the must succinct ones I've read. I've always understood what the transform does, but the nitty gritty on how the equation works was awesome