---
name: "SDL_atan2f"
section: "3"
platform: "linux"
package: "libsdl3-doc"
version: "3.2.10+ds-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/SDL_atan2f"
---

# SDL\_atan2f(3)

Compute the arc tangent of y/x , using the signs of x and y to adjust the result's quadrant.

## NAME

SDL\_atan2f - Compute the arc tangent of **y**/**x** , using the signs of x and y to adjust the result's quadrant.

## HEADER FILE

Defined in SDL3/SDL\_stdinc.h

## SYNOPSIS

```
#include "SDL3/SDL.h"
```

**float SDL\_atan2f(float y, float x);**

## DESCRIPTION

The definition of **z**=**atan2(x,**y) is **y**=**x**tan(z) , where the quadrant of z is determined based on the signs of x and y.

Domain: **-INF**\<=**x**\<=**INF** , **-INF**\<=**y**\<=**INF** Range: **-Pi/2**\<=**y**\<=**Pi/2** This function operates on single-precision floating point values, use

**SDL\_atan2**\
  for double-precision floats.

To calculate the arc tangent of a single value, use  **SDL\_atanf** .

This function may use a different approximation across different versions, platforms and configurations. i.e, it can return a different value given the same input on different machines or operating systems, or if SDL is updated.

## FUNCTION PARAMETERS

- *y*

  floating point value of the numerator (y coordinate).

- *x*

  floating point value of the denominator (x coordinate).

## RETURN VALUE

Returns arc tangent of of **y**/**x** in radians, or, if **x**=**0** , either **-Pi/2** , **0** , or **Pi/2** , depending on the value of **y** .

## THREAD SAFETY

It is safe to call this function from any thread.

## AVAILABILITY

This function is available since SDL 3.2.0.

## SEE ALSO

**•**(3), [**SDL\_atan2**(3)](/SDL_atan2/3.md), **•**(3), [**SDL\_atan**(3)](/SDL_atan/3.md), **•**(3), [**SDL\_tan**(3)](/SDL_tan/3.md)