I think today I had a decisive breakthrough in battle with my continuation problem. There's still some mopping-up to do, and an interesting discrepancy, but in principle, things may finally be working. Three ideas led to today's victory:
- If Y is a function of X (and is monotone, and continuous), then X is a function of Y too. Sometimes, it's easier to hunt for X given Y than for Y given X.
- If you're looking for a small parameter (or one close to 1), try looking for its logarithm instead. Moving from 0.001 to 0.0001 can be problematic, while moving from 3 to 4 is straight-forward.
- Nothing beats having the answer already in hand. It's worth investing time in finding a good initial condition.
- Bonus software engineering lesson: Structure your code right. A clear interface between sections makes it easier to try these things out, and more likely that you'll be home on time for dinner.
Free advice, worth what you paid for it.
Oh yes. Imagine you have a black box sitting in front of you, with a knob and a gauge. Continuation, in simple terms, involves twiddling the knob, and writing down how the value shown on the gauge moves. Sometimes this is linear (a 10% move of the knob gives a 10% change in value), but for "fun" black boxes, that's not the cases.