just like in grad school

Marshall and I (nearly) finished writing the lens-equation-solving part of our plug-in to the Tractor. This reminded me of graduate school, where I spent a lot of time solving the lens equation. One of my first efforts along this line became my first arXiv submission (astro-ph/9311077), which I am proud to say was submitted when the wonderful, wonderful arXiv was in its second year of infancy (and wasn't called arXiv). Today Marshall and I re-discovered that uniquely identifying—by root finding—all the multiple images of a lensed source is non-trivial, especially near cusp caustics! That also reminded me of graduate school, where I worked out and then abandoned dozens of semi-clever techniques.