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From: "ahn567 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libfortran/49336] New: ATAN2  values differ from those specified in documentation
Date: Thu, 09 Jun 2011 00:19:00 -0000	[thread overview]
Message-ID: <bug-49336-4@http.gcc.gnu.org/bugzilla/> (raw)

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49336

           Summary: ATAN2  values differ from those specified in
                    documentation
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ahn567@gmail.com


The documentation for ATAN2(Y,X) says:  

"If Y is zero, then the return value is zero if X is positive and pi if X is
negative."

However, the value returned by  ATAN2(-0d0, -1d0)  is  -pi  (not +pi).
This is for gfortran 4.4.5.

So either the documentation needs fixing (and signed zero explained), 
or the function ATAN2 should be redefined to return values in (-pi,pi]. 

...I'm not sure which is more standard for Fortran.


             reply	other threads:[~2011-06-09  0:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-09  0:19 ahn567 at gmail dot com [this message]
2011-06-09  2:45 ` [Bug libfortran/49336] " kargl at gcc dot gnu.org
2011-06-09  6:05 ` burnus at gcc dot gnu.org
2011-06-10  0:34 ` ahn567 at gmail dot com
2011-11-07 22:26 ` fxcoudert at gcc dot gnu.org
2011-11-07 22:26 ` fxcoudert at gcc dot gnu.org

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