###### (This is the documentation for SDL3, which is the current stable version. SDL2 was the previous version!)

# SDL_atan

Compute the arc tangent of `x`

.

Defined in <SDL3/SDL_stdinc.h>

## Syntax

`double SDL_atan(double x);`

## Function Parameters

double |
**x** |
floating point value. |

## Return Value

(double) Returns arc tangent of of `x`

in radians, or 0 if `x = 0`

.

The definition of `y = atan(x)`

is `x = tan(y)`

.

Domain: `-INF <= x <= INF`

Range: `-Pi/2 <= y <= Pi/2`

This function operates on double-precision floating point values, use SDL_atanf for single-precision floats.

To calculate the arc tangent of y / x, use SDL_atan2.

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.

## Thread Safety

It is safe to call this function from any thread.

## Version

This function is available since SDL 3.1.3.

## See Also

CategoryAPI, CategoryAPIFunction, CategoryStdinc