Note Set 04a: Basic matrix wrangling & the dangers of multiplication

We get back to basics with a howto session on matrix operations starting with scalar multiplication and addition. We then take a look at multiplication starting with the fundamental inner product definition. Matrices do many things like normal numbers but multiplication is the big exception: We see why almost always $BA \ne AB$, even if both products are defined. Next: Advanced Wrangling.
Best consumed by 2016/09/07