Roslin

This morning I gave Django a walk to Roslin, getting this different view of the Pentlands before dropping down to the gunpowder mills in the glen. Unsurprisingly, given all the trees and the time since it last snowed, the view of the mills was unremarkable (see extra). After crossing Roslin village, we went back by bus. I got off a couple of stops early in order to take the three Turf zones I needed to reach rank 53: "Amazing Turfer"! It takes about six months for me to reach a new rank, so this was briefly satisfying. 

After that, I continued with the programming I started yesterday, adding more tests to validate its correctness. However, I wasn't getting the performance that could be expected theoretically. The collaborator who wanted the fix prodded me by reminding me what was possible. Eventually, I spotted the reason, and suddenly I was getting full performance. I also received some excellent results from developer F, which show that for large instances of problems of a major class, his solver is ten times faster than our current solver - which is already the world's best open-source solver for problems in this class. He's been working on it for 18 months, and there's probably another 3-6 months of work before it can be released, but it's excellent and timely news!

Daughter K called in the early evening, and we watched "Vengeance most Fowl" together. The house is not as warm as yesterday, because the problem of the heating system losing pressure is far worse now, presumably due to the increased flow through the system. However, addressing this was discussed yesterday.