On Oct 17, 4:05 am, Ken Schutte <[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. > > As others have said, you can use Python's complex numbers (just write -3 > as -3+0j). If for some reason you don't want to, you can do it all with > reals using Euler's formula, > > (-3)^-4.11111 = (-1)^-4.11111 * 3^-4.11111 > = > e^(j*pi*-4.11111) * 3^-4.11111 > = > (cos(pi*-4.11111) + j*sin(pi*-4.11111)) * 3^-4.11111 > > in Python: > > >>> import math > >>> real_part = (3**-4.11111) * math.cos(-4.11111 * math.pi) > >>> imaj_part = (3**-4.11111) * math.sin(-4.11111 * math.pi) > >>> (real_part,imaj_part) > (0.01026806021211755, -0.0037372276904401318) > > Ken
Thank you for this. Now I need to somehow express this as a real number. For example, I can transform the real and imaginary parts into a polar coordinate giving me the value I want: z = sqrt( real_part**2 + imaj_part**2 ) but this is an absolute terms. How does one determine the correct sign for this value? -- http://mail.python.org/mailman/listinfo/python-list
