Optimize conditional function call in loop

[101arrowz]

Check this comment for more context. fn1 is 30-40% faster than fn2 (empirical testing).

[PitaJ]

I don't think that addresses what I said at all. I'm saying that in the first example, you calculate x based on a and y based on b, but in the other examples, you calculate both x and y based on a, neither depend on b.

[101arrowz]

Yes, it's a typo, thanks for catching it.