[Python-Dev] Re: marshal / unmarshal

"Martin v. Löwis" martin at v.loewis.de
Sat Apr 9 15:32:06 CEST 2005

Skip Montanaro wrote:
>     Martin> Yet, this *still* is a platform dependence. Python makes no
>     Martin> guarantee that 1e1000 is a supported float literal on any
>     Martin> platform, and indeed, on your platform, 1e1000 is not supported
>     Martin> on your platform.
> Are float("inf") and float("nan") supported everywhere? 

I would not expect that, but Tim will correct me if I'm wrong.

> As a starting point can it be agreed on whether they
> should be supported?  (There is a unique IEEE-754 representation for both
> values, right?

Perhaps yes for inf, but I think maybe no for nan. There are multiple
IEEE-754 representations for NaN. However, I understand all NaN are
meant to compare unequal - even if they use the same representation.

> If so, the float("1e10000") == float("inf") in all cases, right?

Currently, not necessarily: if a large-enough exponent is supported
(which might be the case with a IEEE "long double", dunno), 1e10000
would be a regular value.

> That seems like it would be a start in the right direction.

Pieces of it would be a start in the right direction.


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