# Ruby | Math atan() function

• Last Updated : 07 Jan, 2020

The atan() is an inbuilt function in Ruby returns the arc tangent of a number means give a tangent value to this function it will return the angle in radian corresponding to that value. arc tangent is the inverse operation of tangent. This function accepts all numbers in range [-inf, +inf].

Syntax: Math.atan(value)

Parameters: The function accepts one mandatory parameter value whose corresponding angle we have to find.

Return Value: It returns the angle in radians which in range -pi/2 to +pi/2.

Example 1:

 `#Ruby program for atan() function`` ` `#Assigning values``val1 = 1 val2 = 0.5 val3 = -1 val4 = -0.9`` ` `#Prints the atan() value``                                      ``puts` `Math.``atan``(val1)``                                          ``puts` `Math.``atan``(val2)``                                              ``puts` `Math.``atan``(val3)``                                                  ``puts` `Math.``atan``(val4)`

Output:

```0.7853981633974483
0.4636476090008061
-0.7853981633974483
-0.7328151017865066
```

Example 2:

 `#Ruby program for atan() function`` ` `#Assigning values``val1 = 0.9 val2 = 0.2 val3 = -0.78 val4 = -0.32`` ` `#Prints the atan() value``                                           ``puts` `Math.``atan``(val1)``                                               ``puts` `Math.``atan``(val2)``                                                   ``puts` `Math.``atan``(val3)``                                                       ``puts` `Math.``atan``(val4)`

Output:

```0.7328151017865066
0.19739555984988078
-0.6624262938331512
-0.3097029445424562
```

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