Homework #3

Jumped to the homework because I'm running out of time.  Mostly pretty straightforward, but measuring distances for knn was a royal pain on a video screen.

One tip on regression: when I went back to the lecture, I thought the denominator for $w_1$ was $M \sum y_i^2 - (\sum x_i)^2$  It is of course $M \sum x_i^2 - (\sum x_i)^2$.