Re: (long) sNaNs not what they could be... (original) (raw)

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Date: Fri, 15 Oct 2010 18:54:44 -0400 To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx> From: Michel Hack <hack@xxxxxxxxxxxxxx> Subject: (long) sNaNs not what they could be...

. . .

Btw, some machines (HP's PA-RISC if I remember correctly) do use a 1-bit to denote SNaN, and all-ones is an SNaN, but this complicates the Quieting operation, which may have to insert another 1-bit to prevent decaying to Infinity.

Michel.

Oh, Michel, I know this all too well.

I was HP's "man on the 754 committee"
in 1980.

I was on the team that designed that
first generation of floating-point
chips at HP in 1981.

I made that choice.

The wrong one as it happens.


        Dan