Fractional exponents vs. radical form ...

[DrD]

Pardon my English, but math is not my native language:

Frustration: Expressions, (or equations), similar to x^([even numbered numerator]/denominator), when x<0.

An Example:

(-1)^(2/3); ==> (-1/2)+i*sqrt(3)/2
(3) NTHROOT ((-1)^2); ==> 1, the desired result

f(x):=(x^(2/3));
g(x):=((3) NTHROOT (x^2));
subst({f(x), g(x)}, x=(-1)); ==> {((1/2)+(i*sqrt(3)/2))^2,1}

A setting would be nice, that would force fractional exponents, to be the same as their radical form ... not sure how to best define it, but like obscenity, "I know it when I see it!"

-Dale-