four tangent spheres

Given four points in 3D, under what conditions will there exist spheres centered at these points that are mutually tangent?

differential equations for teachers

I'm working on some material on differential equations that is part of a calculus workshop I'm doing next month. I know it's "advanced" but it seems to be the most natural way to use derivative qualitatively. We'll see!

Finished the Baroque Cycle!

The Baroque Cycle is a trilogy by Neal Stephenson that has, among its many subplots, the calculus controversy between Newton and Leibnitz. It took me parts of two years to finish, but it was well worth it. In the end, the distinction between the two is that Newton, the alchemist, lives in a continuous world, while Leibnitz, the monist, is ahead of his time, trying to develop the "Logic Mill" - a pre-Babbage mechanical computer.

Why Calculus Lite?

I teach calculus at different levels at UMass Lowell. Besides the standard science and engineering calculus, I'm involved in a program called Focus on Math in which I happen to be teaching a calculus overview for grade 5-12 teachers. Also, I teach a Mathematica course and do a lot of calculus review to illustrate the software.

I've been meaning to try a blog for a while. I don't know where this will go, but it's started!