http://go-tour-jp.appspot.com/#24

24.go

package main

import (
    "fmt"
    "math"
)

func Sqrt(x float64) float64 {
    z := float64(1)
    for i := 0; i < 10; i++ {
        //fmt.Println(i)
        z2 := math.Float64bits(z)
        z = z - ((math.Pow(z, 2) - x) / (2 * z))
        fmt.Println(math.Float64bits(z))
        if z2 - math.Float64bits(z) <= 1 {
            return z
        }
    }
    return z
}
    

func main() {
    v := 2.0
    fmt.Println(Sqrt(v))
    fmt.Println(math.Sqrt(v))
}