In the morning, arguments continued with Magland about the neuroscience problem of spike sorting. He showed some beautiful visualizations of real spike-train data from live rat brains. We talked about the connection between spike sorting and decision making: Just like in astronomical catalog generation, unless you have a way to deliver a sampling or pdf in catalog space, a spike-sorting algorithm is a decision-making algorithm. As such, it must include a utility!
In the afternoon, I gave the Applied Mathematics Seminar at the Courant Institute at NYU. I spoke about exoplanet search, where we have used lots of applied linear algebra ideas.