simple for wxplot2d rad_cubic and other odd- exp



Problems with exponential function x^(1/3)  - x^(2/3) - ecc. 

If you try to plot function as x^(1/3) , x^2-3*x^(2/3)
wxplot2d plots are wrong (it plots only positive-parts).
This my simplest or simple block correct the exponential
function and so wxplot2d and other in Maxima works fine.

rad(n,x):= block(
rad1(n,x):=float(exp(1/n*log(x))),
rad2(n,x):=float(-exp(1/n*log(-x))),
if x>0 then rad1(n,x)
else rad2(n,x))$

Usage:

x^(1/3)-> rad(3,x)
x^(2/3)-> rad(3,x^2)

I hope that it is useful to someone.

Luigi