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- Subject: Re: Re[2]: NaN in Lua 5.3 Reference Manual
- From: Coda Highland <chighland@...>
- Date: Fri, 23 Jun 2017 14:09:22 -0500
On Fri, Jun 23, 2017 at 1:49 PM, Sean Conner <sean@conman.org> wrote:
> It was thus said that the Great Coda Highland once stated:
>>
>> It actually DOESN'T have a unique bit pattern in IEEE-754. All
>> IEEE-754 numbers with an exponent of all 1's is a NaN, and in fact
>> some VMs (including LuaJIT) exploit this fact to pack 52 bits of
>> useful information into the mantissa instead of storing it externally.
>
> The exponent of all ones represents two concepts----if the mantissa (the
> non-exponent portion) is all zeros, the number is +infinity (or -inifinity
> if the sign bit is set). If the mantissa has any bit set (not all zeros) it
> is then considered NaN.
>
> -spc
>
>
Oops. Thanks for the correction.
/s/ Adam