∂x/∂θ = Chris’ head exploding. I’m pretty sure the last time I did any serious calculus was about 13 years ago; today I got to reacquaint myself with the chain rule and the product rule (at least I could remember how to partially differentiate polynomials). I may have to go to Borders, pick up Calculus for Dummies, and hide it under my desk (so as not to embarrass myself in front of the young whipper-snappers in the room) if this keeps up.