# GoLang – Find Inverse of Tan – Atan() Function – Examples & Explanation

`Atan()` function is used to find the inverse of a tan in Go language. The inverse of a tan is also known as arctan. `Atan()` function is a part of `math` library of Go programming language.

## Syntax of `Atan()` in Go Language

The syntax of `Atan()` function is:

`func Atan(x float64) float64`

Note: `float64` is a data type in go language which has IEEE-754 64-bit floating-point numbers.
Special cases are:
```Atan(±0) = ±0 Atan(±Inf) = ±Pi/2```

## Parameters of `Atan()` Function in Go Language

`x` Any Valid GoLang number ( positive or negative ). This parameter is required.
Note: if the `x` parameter is not a number, `Atan()` function will return an `error`.

## `Atan()` Return Value

`Atan()` function returns a floating point number ( a value of the inverse of tan in radians ).

## GoLang `Atan()` Function Example 1:

```package main

import "fmt"
import "math"

func main() {
var x float64
x = math.Atan(-1)
fmt.Println(x)
}```

Output
`-0.7853981633974483`

## GoLang `Atan()` Function Example 2:

```package main

import "fmt"
import "math"

func main() {
var x float64
x = math.Atan(0)
fmt.Println(x)
}```

Output:
`0`

## GoLang `Atan()` Function Example 3:

```package main
import "fmt"
import "math"
func main() {
var x float64
x = math.Atan(2)
fmt.Println(x)
}```

Output:
`1.1071487177940904`