[Python-ideas] math.inf and math.nan constants

[Chris Barker]

On Wed, Jan 7, 2015 at 11:02 AM, Bruce Leban <bruce at leban.us> wrote:

> There is a problem here but that's not it. The problem is that
>
> float("nan") is float("nan") => False
> math.nan is math.nan => True
>
>
> So is this an attractive nuisance that will make people think they can
> should use x is math.nan instead of math.isnan(x)?
>

This "attractive nuisance" exists for ALL python objects, and is especially
attractive for interned ints and strings.

I have a much harder time getting students to use "is None" than getting
them to not use "is" elsewhere.

My summary:

there isn't a huge reason to add math.nan, but there is essentially zero
cost -- what's the problem?

-Chris



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