Many a times it happens that while solving mathematical expressions we require to calculate the square root of a number.

To solve this issue like other programming language PHP provides us with a built-in function *sqrt()* which can be used to calulate the square root of a number. The *sqrt()* function in PHP is used to calculate the square root of a number.

We already have discussed about sqrt() function in brief in the article PHP | Math functions. In this article we will learn about the pow() function in details.

**Syntax:**

floatsqrt(value)

**Parameters :** This function accepts a single parameter *$value*. It is the number whose square root you want to know.

**Return Value:** It returns a floating point value which is the square root of the argument *$value* passed to it.

Examples:

Input : sqrt(25) Output : 5 Input : sqrt(-25) Output : NaN Input : sqrt(0.09) Output :0.3 Input : sqrt(0) Output : 0

Below programs illustrate the working of sqrt() in PHP:

- When a positive number is passed as a parameter:
`<?php`

`echo`

`(sqrt(25));`

`?>`

Output:

5

- When a negative number is passed as a parameter:
`<?php`

`echo`

`(sqrt(-25));`

`?>`

**Output:**NaN

- When a number with decimal places is passed as a parameter:
`<?php`

`echo`

`(sqrt(0.09));`

`?>`

Output:

0.3

- When zero is passed as a parameter:
`<?php`

`echo`

`(sqrt(0));`

`?>`

Output:

0

**Important Points To Note:**

- sqrt() function is used to calculate the square root of a number.
- It is much more efficient than the generic method of square root calculation.
- Precision depends on the user's precision directive.

**Reference**:

http://php.net/manual/en/function.sqrt.php

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