AstroHackWeek 2017 kicked off today, with Adrian Price-Whelan (Princeton) and I doing a tutorial on machine learning. We introduced a couple of ideas and simple methods, and then we set ten (randomly assigned) groups working on five methods on two different data sets. We didn't get very far! But we tried to get the discussion started.
In the afternoon hacking sessions, Price-Whelan and I looked at some suspcious equations in the famous Binney & Tremaine book, 2ed. In Chapter 4, there are lots of integrals of phase-space densities and we developed an argument that some of these equations must have wrong units. We can't be right—Binney & Tremaine can't be wrong—because all of Chapter 4 follows from these equations. But we don't see what we are doing wrong.
[Note added later: We were wrong and B&T is okay; but they don't define their distribution functions very clearly!]
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