Difficulty with IMPOWER() Worksheet Function

[monirg]

Hello;

1) The cubic root of complex numbers "x+yi" are calculated using IMPOWER().
The w/s function appears to return incorrect values when the coefficients of the complex number are -ve.

2) For example:
A1:: -8+0i
B1::= IMPOWER(A1,1/3)
the function returns: 1. + 1.7320508i
instead of the correct value of -2.

3) The problem appears to be consistent with calculating theta [=atan(y/x)] as "pi" instead of "0" for the above example "-8+0i"

How to fix the problem ??

Thank you kindly.

 

[mortgageman]

<Big Snip>

I will answer to the points 3 and 4 later. Let me tell you, however that I disagree completely with them.

Allow me to answer point 3 if I may, pgc:

Monrig said:

3) My experience with complex numbers in XL environment is rather limited. However, one might reasonably argue that a complex number with zero imaginary coefficient is equivalent to a real number!
Now try =POWER(-8,1/3). You would correctly get -2.0 and not #NUM!

I don't think that is a reasonable argument at all. The value (0 in this case) is less important than the "place holder". The fact that you have written a+bi, even where b is zero, indicates you are talking about a complex number. It's almost like saying one could resaonably argue that 10 is really equivalent to one, since there is only a zero in the one's column.

Why would you expect =power(-8,1/3) to get a #NUM?