Signed zeros: is this a bug?
dickinsm at gmail.com
Sun Mar 11 22:29:48 CET 2007
On Mar 11, 5:15 pm, Tim Peters <tim.... at comcast.net> wrote:
It's a bug that keeps resurfacing, probably because there's no
> way to test that it stays fixed :-( (it's not an accident that the OP
> relied on atan2 to distinguish +0.0 from -0.0! they act the same in
> /almost/ all contexts).
Not an accident, but not a contrived example either. I'd rewritten
all the cmath routines (in pure Python) to be more numerically aware
and use the
`correct' (= those recommended by Kahan) branch cuts. It was in
writing the unit tests for this that the problems above surfaced.
By the way, I don't suppose that anybody would be interested in
a rewritten cmath for Python 2.6? It wouldn't be hard for me to
rewrite what I already have in C, and add suitable documentation
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