This is the mail archive of the glibc-bugs@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[Bug math/13629] clog() returns wrong values around z=1


http://sourceware.org/bugzilla/show_bug.cgi?id=13629

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|aj at suse dot de           |unassigned at sourceware
                   |                            |dot org

--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-03 21:26:56 UTC ---
Confirmed in current source code by inspection.  The implementation approach of
log(hypot) for finding the real part of clog will cause undue overflows for
large input, inaccurate results from undue underflow for subnormal input, and
inaccurate results for z close to |z|=1 (not just close to 1 itself).  The
general case of z close to that circle will be more complicated to fix than the
overflow and underflow cases.

clog10 (a GNU extension, name reserved in ISO C) has the same issues.

-- 
Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]