# StrictMath atan() Method in Java

• Last Updated : 29 Dec, 2021

The java.lang.StrictMath.atan() is an inbuilt method of StrictMath class which is used to return the tangent of a given argument. It returns the angle is within the range of -pi/2 and pi/2. It gives rise to two special results:

• The output is NaN if the passed parameter is a NaN.
• If the passed argument is 0, then the result is also a 0 retaining the same sign as the argument.

Syntax :

`public static double atan(double num)`

Parameters: The method accepts one parameter num of double type and refers to the value whose tangent is to be returned.

Return Value: The method returns the arc tangent value of the argument.

Examples :

```Input: num = 0.61
Output: 0.5477400137159024

Input: num = 0.0
Output: 0.0

Input: num = -71.0
Output: -1.5567127509720364
```

Below programs illustrate the java.lang.StrictMath.atan() method:
Program 1:

## java

 `// Java program to illustrate the``// java.lang.StrictMath.atan()``import` `java.lang.*;`` ` `public` `class` `Geeks {`` ` `    ``public` `static` `void` `main(String[] args)``    ``{`` ` `        ``double` `num1 = ``0.70``, num2 = ``55.00``, num3 = ``0``;`` ` `        ``double` `atanValue = StrictMath.atan(num1);``        ``System.out.println(``"The arc tangent of "` `+ ``                         ``num1 + ``" = "` `+ atanValue);`` ` `        ``atanValue = StrictMath.atan(num2);``        ``System.out.println(``"The arc tangent of "` `+ ``                         ``num2 + ``" = "` `+ atanValue);`` ` `        ``atanValue = StrictMath.atan(num3);``        ``System.out.println(``"The arc tangent of "` `+ ``                          ``num3 + ``" = "` `+ atanValue);``    ``}``}`

Output:

```The arc tangent of 0.7 = 0.6107259643892086
The arc tangent of 55.0 = 1.5526165117219184
The arc tangent of 0.0 = 0.0
```

Program 2:

## java

 `// Java program to illustrate the``// java.lang.StrictMath.atan()``import` `java.lang.*;`` ` `public` `class` `Geeks {`` ` `    ``public` `static` `void` `main(String[] args)``    ``{`` ` `        ``double` `num1 = -``0.52``, num2 = -``71.00``, num3 = ``0``;`` ` `        ``double` `atanValue = StrictMath.atan(num1);``        ``System.out.println(``"The arc tangent of "` `+ ``                           ``num1 + ``" = "` `+ atanValue);`` ` `        ``atanValue = StrictMath.atan(num2);``        ``System.out.println(``"The arc tangent of "` `+ ``                            ``num2 + ``" = "` `+ atanValue);`` ` `        ``atanValue = StrictMath.atan(num3);``        ``System.out.println(``"The arc tangent of "` `+ ``                            ``num3 + ``" = "` `+ atanValue);``    ``}``}`

Output:

```The arc tangent of -0.52 = -0.4795192919925962
The arc tangent of -71.0 = -1.5567127509720364
The arc tangent of 0.0 = 0.0
```

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