From: Rosivaldo Fernandes Alves <rosivaldo.fa@gmail.com>
To: libc-help@sourceware.org
Subject: Complex division implementation: arbitrary sign taking?
Date: Wed, 7 Apr 2021 14:48:02 -0300 [thread overview]
Message-ID: <c1937d79-d631-ae50-c74e-09cf2ece7918@gmail.com> (raw)
While trying to figure out how glibc implements complex division, I've
found divtc3.c, where a division by zero is handled like written below.
if (denom == 0.0 && (!isnan (a) || !isnan (b)))
{
x = copysignl (INFINITY, c) * a;
y = copysignl (INFINITY, c) * b;
}
The other branches of the algorithm handle signs in a very sensible
manner, but the lines above seem rather arbitrary. Why to take the sign
of c for both parts? Why does d play not part at all?
Thanks in advance.
Rosivaldo.
reply other threads:[~2021-04-07 17:48 UTC|newest]
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