[Python-Dev] Not-a-Number (original) (raw)

Steven D'Aprano steve at pearwood.info
Fri Apr 29 03:44:10 CEST 2011

Greg Ewing wrote:

Taking a step back from all this, why does Python allow NaNs to arise from computations at all?

The real question should be, why does Python treat all NANs as signalling NANs instead of quiet NANs? I don't believe this helps anyone.

+Inf and -Inf are arguably useful elements of the algebra, yet Python insists on raising an exception for 1.0./0.0 instead of returning an infinity.

I would argue that Python is wrong to do so.

As I've mentioned a couple of times now, 20 years ago Apple felt that NANs and INFs weren't too complicated for non-programmers using Hypercard. There's no sign that Apple were wrong to expose NANs and INFs to users, no flood of Hypercard users confused by NAN inequality.

-- Steven

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