We had a thunderstorm - with hail - and he hid behind the chair: much better by the fire.
Today I was looking at Lagrange multipliers (M820 - calculus of variations) which I had thought were difficult, was pleasantly surprised to find easy until I then checked the Wikipedia article where such naivity was painfully exposed.
I persevere with "Consistent Quantum Mechanics" (Griffiths) which in these earlier chapters is still a tour around the toolkit. Today I was looking at operator matrix representations for the tensor product of Hilbert spaces. This is not as bad as it sounds, but the reader ends up writing down a whole lot of complicated matrices, unpacking the chapter's compact notation. Like so many things, you feel better when you're done.
