Very happy to notice that Erich's Packing Center (www2.stetson.edu/~efriedma/pac) is still being updated! Two new (and very pretty) packings have been added this year: www2.stetson.edu/~efriedma/tri, www2.stetson.edu/~efriedma/lin

$r=\sqrt{1+\alpha\cos2\theta}.$ All these curves enclose the same area.

The quality of a Fourier approximation of a closed curve $$\gamma:\mathbb S^1\to\mathbb R^2$$ depends heavily on its parametrization. Below: a square approximated with 1, 2, and 3 nonzero Fourier modes.

2. A simple incompressible fluid solver that dramatically reduces the energy loss associated with advection-projection algorithms. This paper was a lot of fun to write; big props to my coauthors Jonas Zehnder and Bernhard Thomaszewski at the U de Montréal.