| msg24193 - (view) |
Author: George Yoshida (quiver)  |
Date: 2005-02-08 16:26 |
| >>> -(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. |
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| msg24194 - (view) |
Author: Björn Lindqvist (sonderblade) |
Date: 2005-02-09 18:54 |
| 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. |
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| msg24195 - (view) |
Author: George Yoshida (quiver) |
Date: 2005-02-10 00:02 |
| 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. |
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| msg24196 - (view) |
Author: George Yoshida (quiver) |
Date: 2005-03-19 17:11 |
| Logged In: YES user_id=671362 Martin, what's your take on this? The representation of '-(1+0j)' has changed since Revision 2.71 (complexobject.c) and you applied the patch. # original patch making Python LC_NUMERIC agnostic http://www.python.org/sf/774665 |
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| msg24197 - (view) |
Author: Martin v. Löwis (loewis) * |
Date: 2005-05-15 07:57 |
| Logged In: YES user_id=21627 What do you think about the patch attached? |
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| msg24198 - (view) |
Author: George Yoshida (quiver) |
Date: 2005-05-15 12:22 |
| Logged In: YES user_id=671362 The fix seems reasonable to me and it passed the test suites. Please apply it. |
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| msg24199 - (view) |
Author: George Yoshida (quiver) |
Date: 2005-09-16 05:02 |
| Logged In: YES user_id=671362 Can anyone else review this patch before the new 2.4 gets released? The patch is ready to be commited. |
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| msg24200 - (view) |
Author: Georg Brandl (georg.brandl) * |
Date: 2005-09-16 06:43 |
| Logged In: YES user_id=1188172 Reviewed and applied in Objects/complexobject.c r2.74, 2.72.2.2. |
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