# StrictMath sqrt() Method in Java

• Last Updated : 03 Aug, 2018

The java.lang.StrictMath.sqrt() is an inbuilt method of StrictMath class in Java which is used to obtain the exact rounded positive square root of a specified double value.

Syntax:

`public static double sqrt(double num)`

Parameters: The function accepts a single parameter num of double type, whose square root is to be returned by the function.

Return Values: This method returns the positive square root of num. it also gives rise to dout special cases:

• The function returns NaN if the argument is NaN or less than zero
• The function returns positive infinity when the argument is positive infinite.
• The function returns zero with the same sign as the argument if the argument is zero
• The result is the double value nearest to the mathematical square root of the argument value.

Examples:

```Input: num = 25
Output: 5.0

Input: -729
Output: NaN
```

Below programs illustrate the use of java.lang.StrictMath.sqrt() method:

Program 1:

 `// Java Program to illustrate``// java.lang.StrictMath.sqrt() function``import` `java.lang.*;`` ` `public` `class` `Geeks {`` ` `    ``public` `static` `void` `main(String[] args)``    ``{`` ` `        ``double` `num1 = ``289``, num2 = -``729``;``        ``double` `num3 = ``0.0``, num4 = ``547.87``;`` ` `        ``// It returns the positive square root``        ``double` `sqrt_Value = StrictMath.sqrt(num1);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num2);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num3);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num4);``        ``System.out.println(``"square root = "` `+ sqrt_Value);``    ``}``}`
Output:
```square root = 17.0
square root = NaN
square root = 0.0
square root = 23.406622994357814
```

Program 2:

 `// Java Program to illustrate``// java.lang.StrictMath.sqrt() function``import` `java.lang.*;`` ` `public` `class` `Geeks {`` ` `    ``public` `static` `void` `main(String[] args)``    ``{`` ` `        ``double` `num1 = ``1160``, num2 = -``97``;``        ``double` `num3 = -``0.0``, num4 = ``144``;``        ``double` `num5 = -``72.18``;`` ` `        ``// It returns the positive square root``        ``double` `sqrt_Value = StrictMath.sqrt(num1);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num2);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num3);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num4);``        ``System.out.println(``"square root = "` `+ sqrt_Value);`` ` `        ``sqrt_Value = StrictMath.sqrt(num5);``        ``System.out.println(``"square root = "` `+ sqrt_Value);``    ``}``}`
Output:
```square root = 34.058772731852805
square root = NaN
square root = -0.0
square root = 12.0
square root = NaN
```

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