I just found this linked from Wikipedia, and wanted to share/tag it for myself.
This describes Moebius transformations, which are maps of the complex plane which have the form

for fixed . This video really emphasizes how anything having to do with the complex numbers is really about rotation.

I don’t think we have a plug-in for [...]

This post, and a few to follow, aren’t going to be about mathematics at all, but rather another subject close to my heart: education. I am going to share some thoughts on education in general and, in particular, the sorry state of public education (in this country and elsewhere, and from kindergarten through college). In [...]