With the very simple code :
package main
import (
"fmt"
"math"
"math/cmplx"
)
func sqrt(x float64) string {
if x < 0 {
return fmt.Sprint(cmplx.Sqrt(complex128(x)))
}
return fmt.Sprint(math.Sqrt(x))
}
func main() {
fmt.Println(sqrt(2), sqrt(-4))
}
I get the following error message :
main.go:11: cannot convert x (type float64) to type complex128
I tried different ways, but couldn't find out how to convert a float64
to complex128
(just to be able to use cmplx.Sqrt()
function on a negative number).
Which is the correct way to handle this ?
You don't really want to convert a
float64
tocomplex128
but rather you want to construct acomplex128
value where you specify the real part.For that can use the builtin
complex()
function:Using it your
sqrt()
function:Try it on the Go Playground.
Note:
You can calculate the square root of a negative
float
number without using complex numbers: it will be a complex value whose real part is0
and imaginary part ismath.Sqrt(-x)i
(so the result:(0+math.Sqrt(-x)i)
):