Mark Dickinson <[EMAIL PROTECTED]> added the comment: Here's a patch giving an alternative implementation of math.fsum; it's based on Tim Peter's suggestions, works mostly with integer arithmetic, and so bypasses problems with double rounding and extended precision floats.
The patch is experimental: it doesn't have sufficient tests, has no documentation, and it adds math.fsum alongside the current math.sum, to make it easy to compare the two implementations. On my MacBook, math.fsum is a factor of 2-3 times slower than math.sum. It's also longer and distinctly less elegant. So its only real advantage is that it should fix the difficulties on x86 hardware. We *really* need to sort math.sum out, one way or another, before the next beta. Georg recently discovered another problem on x86/Linux: see issue 3421. Some options: (1) leave math.sum as it is, skip all tests on x86/Linux, and document the current behaviour. (2) investigate a version of math.sum that plays with the FPU control word to force 53-bit rounding (and round-half-even) (3) replace math.sum with the slower but (presumably) less erratic math.fsum, possibly just as a temporary measure. This would at least get all tests passing. Jean, Raymond: what do you think? Added file: http://bugs.python.org/file10988/fsum7.patch _______________________________________ Python tracker <[EMAIL PROTECTED]> <http://bugs.python.org/issue2819> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com