ENH: Refactor numpy ** operators for numpy scalar integer powers #8231
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This change is the upshot of discussion on the numpy mailing list where it was decided that a numpy scalar integer raised to a negative integer power should raise a ValueError, as do Numpy arrays. In particular, we want numpy scalars and numpy 0-d arrays to have similar behavior. Previously zero was returned for this case.
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OK, I've done an almost minimal change for this PR. The whole |
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Will merge soonish for 1.12.0. |
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The previous behavior depended on whether numpy scalar integers or numpy integer arrays were involved.
For arrays
For scalars
All of these cases now raise a
ValueErrorexcept for those integer combinations whose common type is float, for instance uint64 and int8. It was felt that a simple rule was the best way to go rather than have special exceptions for the integer units. If you need negative powers, use an inexact type.Note that the
np.powerufunc is used for everything. At this point I think it is more important to settle the behavior than optimize for speed. There are now some bits of code I left in that are currently unused.