Copy your Sqrt function from the earlier exercises and modify it to return an error value.

Sqrt should return a non-nil error value when given a negative number, as it doesn't support complex numbers.

Create a new type

type ErrNegativeSqrt float64

and make it an error by giving it a

func (e ErrNegativeSqrt) Error() string

method such that ErrNegativeSqrt(-2).Error() returns "cannot Sqrt negative number: -2".

Note: a call to fmt.Print(e) inside the Error method will send the program into an infinite loop. You can avoid this by converting e first:fmt.Print(float64(e)). Why?

Change your Sqrt function to return an ErrNegativeSqrt value when given a negative number.

package main

import (

    "fmt"

    "strconv"

)

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string{

    if e <  {

        return "cannot Sqrt negative number:" + strconv.FormatFloat(float64(e),'f',,)

    }

    return ""

}

func Sqrt(f float64) (float64, error) {

    var e error

    if f <  {

        return ,ErrNegativeSqrt(f)

    }

    var z float64 =

    for i := ; i < ; i++ {

        z = z - (z*z - f) / ( * z)

    }

    return z,e

}

func main() {

    fmt.Println(Sqrt())

    fmt.Println(Sqrt(-))

}