this is an example that shows how to use newton method by go.

Go_NewtonMethod.go

package main 



import ( 
    "fmt"
    "math"
)

func Newt(x float64) float64 {
    if x == 0 {
        return 0;
    }
    
    z := 1.0
    for i := 0; i < int(x); i++ {
        z = z - (math.Pow(z, 2) - x) / (2 * z)
    }
    
    return z
}

func Sqrt(x float64) float64 {
    return math.Sqrt(x)
}

func main() {
    
    
    fmt.Println("sqrt value", Sqrt(20))
    fmt.Println("sqrt value", Newt(20))
}