Behavior of negative exponentiation inconsistent between integer types #7648

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1. navneethc commented on May 19, 2016

   

   navneethc

   on May 19, 2016

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   I second this.

   Following tested using:
   Python 3.5.1 (Python 3 environment created using Anaconda 4 64-bit)
   Numpy 1.11.0

   In [34]: np.int32(2)**-2
   Out[34]: 0.25
   
   In [35]: np.uint32(2)**-2
   Out[35]: 0
   
   In [36]: np.int64(2)**-2
   Out[36]: 0.25
   
   In [37]: np.uint64(2)**-2
   Out[37]: 0.25
   
   In [38]: np.int16(2)**-2
   Out[38]: 0
   
   In [39]: np.uint16(2)**-2
   Out[39]: 0
   
   In [40]: np.int8(2)**-2
   Out[40]: 0
   
   In [41]: np.uint8(2)**-2
   Out[41]: 0
   
2. ewmoore commented on May 19, 2016

   

   ewmoore

   on May 19, 2016

   Contributor

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   See issue #7449 and PR #7459. The PR fixes this, but could use some review.
3. mhvk commented on May 19, 2016

   

   mhvk

   on May 19, 2016

   Last edited by mhvk

   Contributor

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   Just in case (have to run): Note that the array case should also keep working. In numpy 1.11:

   np.ones((2,), dtype=int) ** -2
   # array([1, 1])
   

   In current master:

   np.ones((2,), dtype=int) ** -2
   # array([0, 0])
   
4. ewmoore commented on May 19, 2016

   

   ewmoore

   on May 19, 2016

   Contributor

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   Gah. That's mine.
5. ewmoore

   added a commit that references this issue on May 19, 2016

   BUG: one to any power is still 1. Broken edgecase for int arrays

   ...

   This issue will close once commit 5cde31b is merged into the 'master' branch.

   5cde31b
6. ewmoore commented on May 19, 2016

   

   ewmoore

   on May 19, 2016

   Contributor

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   See #7651.
7. charris

   added

   06 - Regression

   component: numpy._core

   on May 19, 2016
8. charris

   added this to the 1.11.1 releaseThis milestone has been deleted milestone on May 19, 2016
9. charris

   added

   00 - Bug

   and removed

   06 - Regression

   on May 19, 2016
10. charris

    removed this from the 1.11.1 releaseThis milestone has been deleted milestone on May 19, 2016
11. charris

    closed this as completedin #7651on May 19, 2016