# Ruby | Math atan2() function

• Last Updated : 07 Jan, 2020

The atan2() is an inbuilt function in Ruby returns angent inverse of (y/x), where y is the proportion of the y-coordinate and x is the proportion of the x-coordinate. The numeric value lies between –pi and +pi representing the angle theta of a (x, y) point and positive x-axis. It is the counterclockwise angle, measured in radian, between the positive X-axis, and the point (x, y).

Syntax: Math.atan2(y, x)

Parameters: The function accepts x and y coordinates.

Return Value: It returns returns a numeric value between –pi and +pi representing the angle theta of a (x, y) point and positive x-axis

Example 1:

 `#Ruby program for atan2() function`` ` `#Assigning values``y1 = 10 x1 = 10`` ` `    ``y2``    ``= 15 x2 = 10`` ` `#Prints the atan2() value``              ``puts` `Math.``atan2``(y1, x1)``                  ``puts` `Math.``atan2``(y2, x2)`

Output:

```0.7853981633974483
0.982793723247329
```

Example 2:

 `#Ruby program for atan2() function`` ` `#Assigning values``y1 = 10 x1 = 5`` ` `    ``y2``    ``= 29 x2 = 17`` ` `#Prints the atan2() value``              ``puts` `Math.``atan2``(y1, x1)``                  ``puts` `Math.``atan2``(y2, x2)`

Output:

``` 1.1071487177940904
1.0405805540182667
```
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