John Machin wrote: > On Oct 17, 8:03 am, Steve Holden <[EMAIL PROTECTED]> wrote: >> [EMAIL PROTECTED] wrote: >>> Does anyone know of an approximation to raising a negative base to a >>> fractional exponent? For example, (-3)^-4.11111 since this cannot be >>> computed without using imaginary numbers. Any help is appreciated. >> A couple of questions. >> >> 1. How do you approximate a complex number in the reals? That doesn't >> make sense. >> >> 2. x ^ -4.1111 = 1 / (x ^ 4.1111), so where do complex numbers enter >> into this anyway? >> >> 3. I think you will find the complex numbers start to emerge as you >> explore fractional exponents. > > This is part of the story -- the other part is that the story differs > depending on whether x is positive or negative. > >> This being Python, and an interactive interpreter being available, you >> can always just try it: >> >> >>> -3 ** -4.1111 >> -0.010927147607830808 > > Steve, Trying to memorise the operator precedence table for each of > several languages was never a good idea. I admit advanced age :-) and > give up and use parentheses, just like the OP did: > >>>> (-3)**-4.11111 > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > ValueError: negative number cannot be raised to a fractional power > > Best regards, > John > Well I guess I'd better admit to advances age too. Particularly since there was a python-dev thread about precedence, unaries and exponentiation not too long ago.
regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden Sorry, the dog ate my .sigline so I couldn't cat it -- http://mail.python.org/mailman/listinfo/python-list
