# complx.Phase() Function in Golang with Examples

• Last Updated : 19 Apr, 2020

In Go language, cmplx packages supply basic constants as well as mathematical functions for the complex numbers. The Phase() function in Go language is used to return the phase (also called the argument) of a given number. Moreover, this function is defined under the cmplx package. Here, you need to import “math/cmplx” package in order to use these functions.

Syntax:

```func Phase(x complex128) float64
```

The return value is in the range [-Pi, Pi].

Example 1:

 `// Golang program to illustrate the complex.Phase() function ` ` `  `package main ` ` `  `import ( ` `    ``"fmt"` `    ``"math"` `    ``"math/cmplx"` `) ` ` `  `// Main function  ` `func main() { ` ` `  `    ``// using the function ` `    ``fmt.Printf(``"%.1f"``, cmplx.Phase(1i*math.Pi)+1) ` `} `

Output:

```2.6
```

Example 2:

 `// Golang program to illustrate the complex.Phase() function ` ` `  `package main ` ` `  `import ( ` `    ``"fmt"` `    ``"math"` `    ``"math/cmplx"` `) ` ` `  `// Main function ` `func main() { ` ` `  `    ``// using the function ` `    ``fmt.Printf(``"%.1f, "``, cmplx.Phase(1i*math.Pi)) ` `    ``fmt.Printf(``"%.1f"``, cmplx.Phase(2i*math.Pi)+3) ` `} `

Output:

```1.6, 4.6
```
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