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updated sqrt code to return an error when asked to Sqrt a negative number

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This commit is contained in:
Stephen M. McQuay 2012-08-27 22:52:57 -06:00
parent bea638aa28
commit aaba46344f
1 changed files with 15 additions and 2 deletions
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17
exercises/00-sqrt/go.go
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@ -7,7 +7,17 @@ import (
const min_threshold = 1e-200
func Sqrt(x float64, threshold float64) (z float64, iterations int) {
type ErrNegativeSqrt float64
func (e ErrNegativeSqrt) Error() string {
return fmt.Sprintf("cannot Sqrt negative number: %v", float64(e))
}
func Sqrt(x float64, threshold float64) (z float64, iterations int, err error) {
if x < 0 {
err = ErrNegativeSqrt(x)
return
}
z = x
old_z := z
for {
@ -25,7 +35,10 @@ func main() {
threshold := 1.0
right_answer := math.Sqrt(2)
for threshold > min_threshold {
answer, iterations := Sqrt(2, threshold)
answer, iterations, err := Sqrt(2, threshold)
if err != nil {
panic(err)
}
fmt.Printf("%0.4g %0.4g %0.20f %0.20f %0.2d\n",
threshold, right_answer-answer, right_answer, answer,
iterations)