The **`Atan2`** function in the Go programming language is used to find the arc tangent value of the $x/y$ value, where $x$ and $y$ are the two parameters.

To use the `Atan2` function, you must import the `math` package in your file and access the `Atan2` function within it using the `.` notation (`math.Atan2`). Here, `Atan2` is the actual function, while `math` is the Go package that stores the definition of this function.

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## Syntax

The definition of the `Atan2` function inside the `math` package is shown below:

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## Parameters

The `Atan2` function takes two arguments of type `float64`. The ratio of these two arguments ($y/x$) is then used to calculate the value of the arc tangent.



## Return value
The `Atan2` function returns a single value of type `float64` that represents the arc tangent value of the ratio of the arguments ($y/x$). The possible range of all return values is between *-π* to *π* radians.

Below is a list of special cases in the return values:

* `NAN`:
  * Atan2(y, NaN) = NaN
  * Atan2(NaN, x) = NaN

* `(+-)0`:
   * Atan2(+0, x>=0) = +0
   * Atan2(-0, x>=0) = -0
   * Atan2(y, +Inf) = +0

* `(+-)π`:
   * Atan2(+0, x<=-0) = +π
   * Atan2(-0, x<=-0) = -π 
   * Atan2(y>0, -Inf) = +π
   * Atan2(y<0, -Inf) = -π
     

* `(+-)π/2`:
   * Atan2(y>0, 0) = +π/2
   * Atan2(y<0, 0) = -π/2 
   * Atan2(+Inf, x) = +π/2
   * Atan2(-Inf, x) = -π/2

* `(+-)π/4`:
   * Atan2(+Inf, +Inf) = +π/4        
   * Atan2(-Inf, +Inf) = -π/4 


* `(+-)3π/4`:
    * Atan2(+Inf, -Inf) = 3π/4 
   * Atan2(-Inf, -Inf) = -3π/4 













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## Examples

Below is a simple example in which we use the `Atan2` function to find the arc tangent value with the parameters -25 and 25:

package main

import "fmt"
import  "math"


func main() {
	
	x := math.Atan2(-25, 25)
	fmt.Println(x)
} 

The following example shows that `NAN` is returned whenever there is `NAN` in any of the  arguments:

package main

import "fmt"
import  "math"


func main() {
	
	x := math.Atan2(math.NaN(), 25)
	fmt.Println(x)
	
	y := math.Atan2(25, math.NaN())
	fmt.Println(y)
} 

What is the Atan2 function in Golang?

Atan2 in Go finds the arc tangent of y/x using two float64 arguments, returning values from -π to π.