On Tue, Feb 18, 2014 at 9:51 AM, Sturla Molden <sturla.mol...@gmail.com> wrote: > Charles R Harris <charlesr.har...@gmail.com> wrote: >> This is apropos issue #899 <<a >> href="https://github.com/numpy/numpy/issues/899";>https://github.com/numpy/numpy/issues/899</a>>, >> where it is suggested that power promote integers to float. That sounds >> reasonable to me, but such a change in behavior makes it a bit iffy. >> >> Thoughts? > > Numpy should do the same as Python does.
That's problematic because Python's behavior is value dependent. Python 3.3.1 (default, May 16 2013, 17:20:13) [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> 2 ** 2 4 >>> 2 ** -2 0.25 That's fine if you only have one value for each operand. When you have multiple values for each operand, say an exponent array containing both positive and negative integers, that becomes a problem. Generally, we try to make ufuncs return types that are predictable from the types of the operands, not the values of the operands. I am -1 on the proposal to make power(x:int, y:int) always return a float. It is usually trivial to just make the exponent a float if one wants a float returned. Or we could introduce an fpow() that always coerces the inputs to the best inexact type. -- Robert Kern _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
