On Tue, Feb 27, 2018 at 2:02 AM, bartc <b...@freeuk.com> wrote: > On 26/02/2018 14:04, bartc wrote: >> >> On 26/02/2018 13:42, Ned Batchelder wrote: > > >> Well, once you notice that the >>> >>> Python code had N=1e5, and the C code had N=1e9 :) If you want to >>> experiment, with N=1e5, the final number should be 5255210926702073855. >> >> >> OK, I'll try that. > > > I have that Python version working now. It's necessary to apply that masking > function to wherever numbers can get bigger. > > I don't know how long a 1-billion loop will take, but a 10-million loop took > 46 seconds on Python 3.6, and 21 seconds on PyPy 2.7 from a couple of years > ago. (And on Windows, which has a somewhat slower CPython than Linux.)
You're still reimplementing the C code in Python, which is inefficient. Have you considered going back to the *actual algorithm* and implementing that idiomatically in Python? I think you'll find that (a) the code is more readable, and (b) the run time is much lower. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
