This is more of a primer on "the first two years of college mathematics" than a primer for Machine Learning, honestly. Still, not a bad resource.
It would really be helpful if such mathematical papers included the pronounciation of those greek (or whatever made-up) letters at least once when they are first used.
Is there a version including the figures?
Typo: the second requirement for pseudo-inverses should be Adagger A Adagger = Adagger, not A.
nice, but: "probability is currently left off"
Two good probability cheat sheets (not primers, though) are