Created
October 10, 2016 09:16
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A Tour of Go Exercise: Errors
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package main | |
import ( | |
"fmt" | |
"math" | |
) | |
type ErrNegativeSqrt float64 | |
func (e ErrNegativeSqrt) Error() string { | |
return fmt.Sprintf("cannot Sqrt nagative number: %g", e) | |
} | |
func Sqrt(x float64) (float64, error) { | |
z := 1.0 | |
if x < 0 { | |
return 0, ErrNegativeSqrt(x) | |
} | |
for { | |
z2 := z - (z * z - x) / (z * 2) | |
if math.Abs(z2 - z) < 1e-10 { | |
break | |
} | |
z = z2 | |
} | |
return z, nil | |
} | |
func main() { | |
fmt.Println(Sqrt(2)) | |
fmt.Println(math.Sqrt(2)) | |
fmt.Println(Sqrt(-2)) | |
} |
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