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From: "jvdelisle at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug testsuite/32057] Random failure on gfortran.dg/secnds.f
Date: Wed, 30 May 2007 03:37:00 -0000 [thread overview]
Message-ID: <20070530033709.20680.qmail@sourceware.org> (raw)
In-Reply-To: <bug-32057-682@http.gcc.gnu.org/bugzilla/>
------- Comment #6 from jvdelisle at gcc dot gnu dot org 2007-05-30 03:37 -------
I modified the program given in comment #4 to display the exact values at the
end of the cycle along with the three methods. Method "a" and method "c" give
identical results. Method "b" has a different phase and its the end point
sooner. The exact true value is shown in the fourth column of the output
below.
-- snippet --
a = 3600.0*real(m)+ 60.0*real(l) + real(k) + 0.001*real(j)
b = 0.001*real(j) + real(k) + 60.0*real(l) + 3600.0*real(m)
c = real(3600*m + 60*l + k)
c = c + real(j)/1000.0
exact1 = 3600*m + 60*l + k
exact2 = j
write(6,100)a, b, c, exact1, exact2
100 format (3(f11.5,2x),i5,".",i3)
Result:
86399.98438 86399.98438 86399.98438 86399.988
86399.99219 86399.99219 86399.99219 86399.989
86399.99219 86399.99219 86399.99219 86399.990
86399.99219 86399.99219 86399.99219 86399.991
86399.99219 86399.99219 86399.99219 86399.992
86399.99219 86399.99219 86399.99219 86399.993
86399.99219 86399.99219 86399.99219 86399.994
86399.99219 86399.99219 86399.99219 86399.995
86399.99219 86400.00000 86399.99219 86399.996
86400.00000 86400.00000 86400.00000 86399.997
86400.00000 86400.00000 86400.00000 86399.998
86400.00000 86400.00000 86400.00000 86399.999
a and c are actually a little more accurate at the end. Its also interesting
that this deviation between the methods appears to happen only near the end of
the sequence. I have visually scanned in quite a few places and all three are
identical until this point.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32057
next prev parent reply other threads:[~2007-05-30 3:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-23 13:52 [Bug testsuite/32057] New: " hjl at lucon dot org
2007-05-23 14:35 ` [Bug testsuite/32057] " dominiq at lps dot ens dot fr
2007-05-23 15:06 ` kargl at gcc dot gnu dot org
2007-05-28 19:53 ` dominiq at lps dot ens dot fr
2007-05-28 22:15 ` tkoenig at gcc dot gnu dot org
2007-05-29 20:25 ` dominiq at lps dot ens dot fr
2007-05-30 2:10 ` jvdelisle at gcc dot gnu dot org
2007-05-30 3:37 ` jvdelisle at gcc dot gnu dot org [this message]
2007-05-30 21:35 ` dominiq at lps dot ens dot fr
2007-06-03 17:07 ` pinskia at gcc dot gnu dot org
2007-06-04 8:37 ` pinskia at gcc dot gnu dot org
2007-06-04 16:11 ` pinskia at gcc dot gnu dot org
2007-06-06 0:54 ` jvdelisle at gcc dot gnu dot org
2007-06-06 1:26 ` jvdelisle at gcc dot gnu dot org
2007-06-19 17:11 ` rob1weld at aol dot com
2007-06-20 22:33 ` rob1weld at aol dot com
2007-06-21 1:06 ` jvdelisle at gcc dot gnu dot org
2007-06-25 3:03 ` jvdelisle at gcc dot gnu dot org
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