A Tour of Go. Advanced Exercise: Complex cube roots. Let's explore Go's built-in support for complex numbers via the complex64 and complex128 types. For cube roots, Newton's method amounts to repeating: Find the cube root of 2, just to make sure the algorithm works. There is a Pow function in the math/cmplx package.

exercise-48.go

package main

import (
    "fmt"
    "math"
    "math/cmplx"
)

func Cbrt(x complex128) complex128 {
    z := complex128(1)
    for i := 1; i <= 10; i++ {
        z = z - (cmplx.Pow(z, 3) - x) / (3 * z * z)
    }
    return z
}

func main() {
    fmt.Println(Cbrt(2))
    fmt.Println(math.Cbrt(2))
}