"Mark Dickinson" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] On May 11, 9:36 pm, "Terry Reedy" <[EMAIL PROTECTED]> wrote: |> Do you have in mind any situations in which it is advantageous to have 0**0 |> undefined?
| (Playing devil's advocate here.) If you regard x**y as exp(y*log(x)) Which, of course, I was not, but for the sake of discussion.... | then it's not at all clear that 0.**0. should be considered well-defined. Then it seems equally dubious that 0.**y, y>0, should be well-defined. It seems to me that lim as x goes to 0. exp(y*log(x)) is equally well defined whether y is 0 or not, even though there is a discontinuity in the limit. . ... | The big problem here is that the power operation is really trying | to combine two subtly different functionalities (integer powers | and real powers), with quite distinct use-cases, into a single | function. Which leads to problems: witness the mess that's | C99's pow specification: why does it make sense for (-2.0)**2.0 to | return 4.0, while (-2.0)**1.999999999 returns NaN? 2.5 raises an exception. In 3.0, >>> (-2)**1.99999999 (3.9999999722741113-1.2566370355167477e-07j) | Incidentally, the decimal module is slightly schizophrenic about this: That module follows the IBM-led standard, no matter how crazy. Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
