# GoLang – Find Arc Tangent – Atan2() Function – Examples & Explanation

`Atan2()` function is used to find the arc tangent for the given inputs (`y/x` – parameters) in Go language.
The standard math package of Go programming language has `Atan2()` function. The purpose of this function is to find the arc tangent of y/x and it will also find the quadrant of the return value (output) by using the signs of both arguments (x and y).

## Syntax of `Atan2()` Function in Go Language

The syntax of `Atan2()` function in Go Language is:

```func Atan2(y, x float64) float64
```

Note: `float64` is a data type in Go language which has IEEE-754 64-bit floating-point numbers.
Special cases are:
``` Atan2(y, NaN) = NaN Atan2(NaN, x) = NaN Atan2(+0, x>=0) = +0 Atan2(-0, x>=0) = -0 Atan2(+0, x<=-0) = +Pi Atan2(-0, x<=-0) = -Pi Atan2(y>0, 0) = +Pi/2 Atan2(y<0, 0) = -Pi/2 Atan2(+Inf, +Inf) = +Pi/4 Atan2(-Inf, +Inf) = -Pi/4 Atan2(+Inf, -Inf) = 3Pi/4 Atan2(-Inf, -Inf) = -3Pi/4 Atan2(y, +Inf) = 0 Atan2(y>0, -Inf) = +Pi Atan2(y<0, -Inf) = -Pi Atan2(+Inf, x) = +Pi/2 Atan2(-Inf, x) = -Pi/2 ```

## Parameters of `Atan2()` Function in Go Language

`x , y` – Where both `x` and `y` is any Valid `float64` Input value. These parameters are required.

## Error Handling

If the `x ` or `y ` parameter are not numbers (numeric values) `Atan2()` function returns an `error `.
If there is no argument (`x,y` – input value) passes to the function, then the compiler will produce an `error`.

## Return Value of `Atan2()` Function in Go Language

`Atan2()` function will returns the arc tangent of the given inputs(`x ` and `y`– parameters). It uses the signs of two inputs to determine the quadrant of then return value.

## GoLang `Atan2()` Function Example 1

```package main

import "fmt"
import "math"

func main() {
var x float64
x = math.Atan2(0,0)
fmt.Println(x)
}
```

Output:
` 0`

## GoLang `Atan2()` Function Example 2

```package main

import "fmt"
import "math"

func main() {
var x float64
x = math.Atan2(-8,9)
fmt.Println(x)
}
```

Output:
` -0.7266423406817255`

## GoLang `Atan2() ` Function Example 3

```package main

import "fmt"
import "math"

func main() {
var x float64
x = math.Atan2(10,4)
fmt.Println(x)
}
```

Output:
`1.1902899496825317`