Dieter Kaiser wrote:
> Because I am working again on the function $csign which should give correct
> answers for complex expressions I regognized the following problem:
>
> This result is wrong:
>
> (%i53) sign((-1)^(1/3));
> (%o53) neg
>
> When we look at the expression we get a wrong result too:
>
> (%i54) (-1)^(1/3);
> (%o54) -1
>
... snip
There are 3 cube roots of -1. If you only know about real numbers, then
-1 is the obvious one.
If you want a generator of all 3 roots, then -1 is the wrong one.
If you want to be correct, you may need to supply a multiple-value
object with 3 roots in it, like
RootOf[x^3+1=0]...
RJF