23.go

// http://go-tour-jp.appspot.com/#23

package main

import (
    "fmt"
    "math"
)

func Sqrt(x float64) float64 {
    z := 1.0
    for i := 0; i < 10; i++ {
        z = z - ((z*z - x) / (2*z))
    }
    return z
}

func Sqrt2(x float64) (float64, int) {
    i := 0
    z := 1.0
    for {
        i++
        if zz := z - ((z*z - x) / (2*z)); math.Abs(zz-z) < 0.0001 {
            break
        } else {
            z = zz
        }
    }
    return z, i
}

func main() {
    for i := 1; i < 10; i++ {
        // Pattern A
        // fmt.Println(i, Sqrt(float64(i)))
        
        // Pattern B
        z, n := Sqrt2(float64(i))
        fmt.Println(i, z, n)
    }
}