Can you determine the sign of the polar form of a complex number?

[Roy Smith]

In article <1192629071.834342.243370 at i38g2000prf.googlegroups.com>,
 schaefer.mp at gmail.com wrote:

> Just to clarify what I'm after:
> 
> If you plot (-3)^n where n is a set of negative real numbers between 0
> and -20 for example, then you get a discontinuos line due to the
> problem mentioned above with fractional exponents. However, you can
> compute what the correct absolute value of the the missing points
> should be (see z2 above for an example), but I would like to know how
> to determine what the correct sign of z2 should be so that it fits the
> graph.

You need to ask this question on a math group.  It's not a Python question 
at all.