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Created on 2018-08-05 07:44 by qq100460045, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Messages (2) | |||
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| msg323136 - (view) | Author: Yiwei Guo (qq100460045) | Date: 2018-08-05 07:46 | |
the answer of 1.2%0.2 should be zero |
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| msg323137 - (view) | Author: Mark Dickinson (mark.dickinson) *  |
Date: 2018-08-05 07:58 | |
This isn't a bug: in short, you're evaluating a discontinuous function very close to a discontinuity; the errors inherent in floating-point arithmetic put you the "wrong" side of the discontinuity. Or more simply, with binary floating-point, What You See Is Not What You Get. When you type 1.2, the value actually stored is the closest values that's exactly representable as a float, which turns out to be 1.1999999999999999555910790149937383830547332763671875. Similarly, the value actually stored for 0.2 is 0.200000000000000011102230246251565404236316680908203125. And 1.1999999999999999555910790149937383830547332763671875 % 0.200000000000000011102230246251565404236316680908203125 is 0.199999999999999900079927783735911361873149871826171875. Some references: https://docs.python.org/3/tutorial/floatingpoint.html https://docs.python.org/3/reference/expressions.html#id17 |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:04 | admin | set | github: 78518 |
| 2018-08-05 07:58:54 | mark.dickinson | set | status: open -> closed nosy: + mark.dickinson messages: + msg323137 resolution: not a bug stage: resolved |
| 2018-08-05 07:46:13 | qq100460045 | set | messages: + msg323136 |
| 2018-08-05 07:44:45 | qq100460045 | create | |