How to get only real output from (-3)^(1/3)

(-3)^(1/3)

ans = 0.7211 + 1.2490i

I need the ans: -1.44224957.

Answer 1

[Steven Lord]

You can use the nthroot function.

y = nthroot(-3, 3)

y = -1.4422

[Walter Roberson]

... I went looking for that, as I thought I remembered it existing. It is not mentioned in the documentation for power() or realroot() .

[Apurbo Roy Chowdhury]

nthroot worked, thanks.

Answer 2

[Walter Roberson]

format long g
syms x
solve(x^3==-3 & imag(x) == 0)

ans = 

double(ans)

ans = 
         -1.44224957030741

[Apurbo Roy Chowdhury]

That worked.. But I needed a function g(x) to always give real output.

syms x;
g(x) = x^(1/3);
double(g(-1))

ans = 0.5000 + 0.8660i

Any solution?

[Wan Ji]

solve it with real syms

syms x real; % add real to make sure it is real
% following is what you want to
g(x) = ...;
x = solve(g(x)==x^(1/3))

[Apurbo Roy Chowdhury]

It shows x=0.