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From: "carlos at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/15536] ulp (0x0.0p0) is not FP_SUBNORMAL!
Date: Fri, 31 May 2013 05:39:00 -0000
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http://sourceware.org/bugzilla/show_bug.cgi?id=15536

Carlos O'Donell <carlos at redhat dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |joseph at codesourcery dot com

--- Comment #2 from Carlos O'Donell <carlos at redhat dot com> ---
Is there a publicly available standard that describes IBM extended precision
long doubles?

The smallest value I can compute is 2^(-1075):
4.94065645841246544177e-324
0x0.00000000000010000000p-1022

The smallest computed value matches the AIX expectations for the, I assume,
similar type.

I'm going to go with the smallest computed value as ulp of zero. 

Why? 

Because the first double represents the number, and if it's mantissa is zero
and the exponent is zero, then it's zero. The extra precision from the second
double is useless for subnormal values. Therefore the smallest subnormal is
identical to that for double.

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