A Tour of Go Exercise: Errors

Exercise: Errors

これにエラー処理を追加する

package main

import (
    "fmt"
    "math"
)

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string {
    return fmt.Sprintf("cannot Sqrt nagative number: %g", float64(e))
}

func Sqrt(x float64) (float64, error) {
    if x < 0 {
    	return 0, ErrNegativeSqrt(x)
    }
    z := float64(2.)
    s := float64(0)
    for i := 0; i < 10; i++ {
        z = z - (z*z - x)/(2*z)
        if math.Abs(z - s) < 1e-10 {
            break;
        }
        s = z
    }
    return z, nil
}


func main() {
    fmt.Println(Sqrt(2))
    fmt.Println(Sqrt(-2))
}