On Mon, 2 Oct 2017 09:49 am, Ben Bacarisse wrote: > Daniel Bastos <dbas...@toledo.com> writes: > >> def make_sequence_non_recursive(N, x0 = 2, c = -1): >> "What's wrong with this function? It's very slow." >> last = x0 >> def sequence(): >> nonlocal last >> next = last >> last = last**2 + c >> return next % N >> return sequence >> >> It crawls pretty soon. Please advise? > > A mathematical rather than Python answer...
Which is the best sort of answer. When possible, simplifying your algorithm is better than speeding up your code. > change it to > > last = (last**2 + c) % N > return next Better: last = (pow(last, 2, N) + (2 % N)) % N will almost certainly be faster for large values of last. -- Steve “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse. -- https://mail.python.org/mailman/listinfo/python-list
