Mark Dickinson <dicki...@gmail.com> added the comment: > * possibly providing a C version of rnd2()
If recoding in C is acceptable, I think there may be better ( = simpler and faster) ways than doing a direct translation of rnd2. For example, for small k, the following algorithm for randrange(k) suffices: - take a single 32-bit deviate (generated using genrand_int32) - multiply by k (a 32-by-32 to 64-bit widening multiply) and return the high 32-bits of the result, provided that the bottom half of the product is <= 2**32 - k (almost always true, for small k). - consume extra random words as necessary in the case that the bottom half of the product is > 2**32 - k. I can provide code (with that 3rd step fully expanded) if you're interested in this approach. This is likely to be significantly faster than a direct translation of rnd32, since in the common case it requires only: one 32-bit deviate from MT, one integer multiplication, one subtraction, and one comparison. By comparison, rnd2 uses (at least) two 32-bit deviates and massages them into a float, before doing arithmetic with that float. Though it's possible (even probable) that any speed gain would be insignificant in comparison to the rest of the Python machinery involved in a single randrange call. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue9025> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
