From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <glibc-bugs-return-622-listarch-glibc-bugs=sources.redhat.com@sources.redhat.com>
Received: (qmail 10345 invoked by alias); 9 Sep 2004 06:46:23 -0000
Mailing-List: contact glibc-bugs-help@sources.redhat.com; run by ezmlm
Precedence: bulk
List-Subscribe: <mailto:glibc-bugs-subscribe@sources.redhat.com>
List-Post: <mailto:glibc-bugs@sources.redhat.com>
List-Help: <mailto:glibc-bugs-help@sources.redhat.com>, <http://sources.redhat.com/lists.html#faqs>
Sender: glibc-bugs-owner@sources.redhat.com
Received: (qmail 10324 invoked by uid 48); 9 Sep 2004 06:46:21 -0000
Date: Thu, 09 Sep 2004 06:46:00 -0000
From: "rth at gcc dot gnu dot org" <sourceware-bugzilla@sources.redhat.com>
To: glibc-bugs@sources.redhat.com
Message-ID: <20040909064620.376.rth@gcc.gnu.org>
Reply-To: sourceware-bugzilla@sources.redhat.com
Subject: [Bug math/376] New: fdim(+inf, +inf) yields NaN instead of 0.0
X-Bugzilla-Reason: CC
X-SW-Source: 2004-09/txt/msg00038.txt.bz2
List-Id: <glibc-bugs.sourceware.org>

C99 7.12.12.1 says the result is

  x - y   if x > y
  +0      if x <= y

This says to me that fdim(+inf, +inf) = 0.0, not NaN as currently reported.
Comparisons between infinities are strictly defined, even though subtracting
them yields NaN.

Except for the out-of-line routines that use fpclassify (why?) it seems as
if we just need to change the condition on the ?: from < to <=.

-- 
           Summary: fdim(+inf, +inf) yields NaN instead of 0.0
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: minor
          Priority: P2
         Component: math
        AssignedTo: aj at suse dot de
        ReportedBy: rth at gcc dot gnu dot org
                CC: glibc-bugs at sources dot redhat dot com


http://sources.redhat.com/bugzilla/show_bug.cgi?id=376

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.