Python's builtin 3-argument pow() exists because, e.g.,
pow(3L, 500, 7) 2L
can be done very much faster, and with much less memory, than
3L**500 % 7 2L
There isn't any compelling use I know of for 3-arg pow() given float arguments, though, and what you get back is a platform-dependent accident:
pow(3., 500., 7.) 4.0
You may get some other integer there, or an Infinity or a NaN, depending on the Python release, and the compiler used to build Python, and the configuration of your libm. That example was done under CVS 2.2a2+ on Windows; here's the same thing but under 2.2.1:
pow(3., 500., 7.) 0.0
Since 3-argument float pow() *appears* to be at best useless, I'm taking it away in 2.2a3, unless someone can testify to a reasonable use case that's actually used. more-trouble-than-it's-worth-if-it-isn't-worth-anything-ly y'rs - tim