Re: Geometry test on NetBSD (was Re: [HACKERS] RC1?)

At 1:15 AM -0500 11/20/02, Tom Lane wrote:
>Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
>> Tom, can you clarify why -0 is valid.
>
>The IEEE spec absolutely thinks that -0 and +0 are distinct entities.
>I don't remember why, at one in the morning ... but if you insist I'm
>sure that plenty sufficient numerical-analysis reasons can be produced.
>The guys who wrote that spec knew what they were doing (that's why it's
>been adopted so universally).

It's so that 1/(1/-infinity) == -infinity. There are probably other
reasons as well.

I'm just guessing here, but it's possible NetBSD acquired the bug by
trying to be functional on non-IEEE hardware. I hope that whoever
found the problem (I don't see that in this thread) filed a bug
report with NetBSD.
--
The opinions expressed in this message are mine,
not those of Caltech, JPL, NASA, or the US Government.
Henry(dot)B(dot)Hotz(at)jpl(dot)nasa(dot)gov, or hbhotz(at)oxy(dot)edu