Grading

I don't have to grade.  But sometimes I like to help my friends grade the radiation labs.  It is kinda fun in its way - everybody gets together with a six pack or two and goes to town.  I'm classy - I write (illegibly) in red pen, but then give them a sticker.  You get a better sticker if you grade is lower; those foo's getting A's only get a star.  Do badly, and you might get a dinosaur.  Why a dinosaur?  Toad told me at one point that whenever I don't know how to answer a test question I should just draw a dinosaur.

I spent the entire day debugging my finite difference code because I forgot a minus sign.  On a related note I learned a little bit about Jacobian Free Newton Krylov methods for solving coupled physics problems.  The basic gist is to ignore the non-diagonal element of the Jacobian, which makes it quickly possible to find a solution to multi-physics problems.  (The general idea is to have a system Jx=S, where J is the Jacobian, x is state vectors (temperature,concentrations,stresses), and S is the source term.  It them comes to solving the matrix system, which is much faster if it is diagonally dominant and sparse.)  This seems like something I want to implement for Blue Box.