ʕ◔ϖ◔ʔ From http://go-tour-jp.appspot.com/#48

48_complex_cube_roots

package main

import (
    "fmt"
    "math/cmplx"
)

func Cbrt(x complex128) complex128 {
    var z complex128 = 1.0
    for {
        z = z - ((cmplx.Pow(z, 3.0)-x)/(3.0*cmplx.Pow(z, 2.0)))
        
        fmt.Println(z, cmplx.Pow(z, 3.0))
        
        if cmplx.Abs(x - cmplx.Pow(z, 3.0)) < 0.000000000001 {
            break
        }
    }
    
    return z
}

func main() {
    fmt.Println(Cbrt(64))
}