PyWart: Language missing maximum constant of numeric types!

Steven D'Aprano steve+comp.lang.python at pearwood.info
Fri Feb 24 23:45:53 CET 2012


On Fri, 24 Feb 2012 09:23:08 -0700, Michael Torrie wrote:

> All this reminds me of the original cray supercomputers.  They didn't
> use twos compliment for integers so they had two representations of zero
> (+0 and -0).  Made programming a bit tricky.

While there is only one integer zero, I would like to point out that in 
floating point, there are usually two zeroes, -0.0 and +0.0, and that 
this is by design and a feature, not an accident or a bug.

Well-written floating point functions should keep the sign when they 
underflow, e.g.:

py> 1e-200 * 1e-200
0.0
py> 1e-200 * -1e-200
-0.0

and well-written functions should honour those separate zeroes because 
sometimes it makes a difference.



-- 
Steven



More information about the Python-list mailing list