[Sbcl-devel] Re: Printing/reading INF and NaN without #.

[Michael H. <mw...@py...>]

Raymond Toy <ray...@er...> writes:

>>>>>> "Mario" == Mario S Mommer <mm...@co...> writes:
>
>     Mario> I like the +I.0f+0 etc. style proposed by Christophe a little bit
>     Mario> better. For NaNs one could use something like N.0d+<char>, where
>     Mario> <char> is a one-char abbrev. of whatever additional attribute is
>     Mario> appropriate.
>
> The entire mantissa of the NaN could contain information.  So a
> one-char abbreviation isn't enough.  You need all the bits.

In some sense :)

> However, I'm not aware of any processor that actually tells you what
> it encodes in the bits, if anything.

I didn't think the intent was so much for processors to use these bits
as libraries -- I think the bits get carried through computations in a
defined way, so you could potentially tell which routine produced the
NaN.  I don't think people actually do this, either, mind, though on
Windows there are at least two printed representations for NaN...

Oh, and most processor documentation will tell you the difference
between a SNaN and a QNaN.

Cheers,
mwh

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