Bugs item #1118729, was opened at 2005-02-09 01:26 Message generated for change (Comment added) made by quiver You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1118729&group_id=5470
Category: Python Interpreter Core Group: Python 2.4 Status: Open Resolution: None Priority: 5 Submitted By: George Yoshida (quiver) Assigned to: Nobody/Anonymous (nobody) Summary: Error in representation of complex numbers(again) Initial Comment: >>> -(1+0j) (-1+-0j) I encountered this while I was calculating conjugate of complex numbers(e.g. z.conjugate()). Related bug * http://www.python.org/sf/1013908 One thing to note is that -(0j) can return 0j or -0j dependeing on OSes. Confirmed on SuSE 9.1 & cygwin. ---------------------------------------------------------------------- >Comment By: George Yoshida (quiver) Date: 2005-02-10 09:02 Message: Logged In: YES user_id=671362 Hi, Björn. Sorry, not to be clear about what my complaint is. I'm not talking about if -(0j) should be 0j or -0j. It's been that way for a long time, so changing it would break old codes. My point is the signature of imaginary part. As you can see, it's represented as '+-'. Before the commit of patch #774665, it was represented as '-1-0j'. But after that, '-1+-0j'. If you test it with Python <= 2.3, you'll get (-1-0j) and I think this is how -(1+0j) should be represented on machines where - (0j) is represented as -0j. ---------------------------------------------------------------------- Comment By: Björn Lindqvist (sonderblade) Date: 2005-02-10 03:54 Message: Logged In: YES user_id=51702 What you are seeing is negative zero (-0.0). It is distinct from positive zero (0.0) but 0.0 == -0.0 is always true. On some machines you can also see it by typing: >>> -0.0 -0.0 On other machines you will see "0.0" instead. You can also try printf("%f\n", -0.0); and you will notice the same thing. So I'm not sure it is a bug per se. However, it can be worked around by adding "if (v->cval.imag == 0.) v->cval.imag = 0.0;" to complexobject.c, assuming ofcourse it is OK to change negative zeros to positive ones. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1118729&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
