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[Bug libfortran/49336] New: ATAN2 values differ from those specified in documentation
- From: "ahn567 at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 9 Jun 2011 00:19:16 +0000
- Subject: [Bug libfortran/49336] New: ATAN2 values differ from those specified in documentation
- Auto-submitted: auto-generated
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.