# PHP sqrt() Function

PHPServer Side ProgrammingProgramming

## Definition and Usage

The sqrt() function returns square root of a positive float number. Since square root for negative number is not defined, it returns NAN. This is one of the most commonly used functions.

This function always returns a floating point number.

sqrt ( float $arg ) : float ## Parameters Sr.NoParameter & Description 1arg a number whose square root is to be obtained ## Return Values PHP sqrt() function returns square root of the given arg number. For negative number, the function returns NAN. ## PHP Version This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x. ## Example Live Demo Following example calculate square root of 100− <?php$arg = 100;
echo "Square root of " . $arg . "=" . sqrt($arg) . "\n";
?>

## Output

This will produce following result −

Square root of 100=10

## Example

Live Demo

For sqrt(2), 1/sqrt(2) and sqrt(3), PHP has special predefined constants M_SQRT2, M_SQRT1_2 and M_SQRT3 respectively −

<?php
echo "sqrt(2) = " . sqrt(2) . "\n";
echo "M_SQRT2 = " . M_SQRT2. "\n";
echo "sqrt(3) = " . sqrt(3) . "\n";
echo "M_SQRT3 = " . M_SQRT3 . "\n";
echo "1/sqrt(2)) = " . 1/sqrt(2) . "\n";
echo "M_SQRT1_2 = " . M_SQRT1_2 . "\n";
?>

## Output

This will produce following result −

sqrt(2) = 1.4142135623731
M_SQRT2 = 1.4142135623731
sqrt(3) = 1.7320508075689
M_SQRT3 = 1.7320508075689
1/sqrt(2)) = 0.70710678118655
M_SQRT1_2 = 0.70710678118655

## Example

Live Demo

The mathematical constants M_SQRTPI and M_2_SQRTPI represent values of sqrt(Π) and 2/sqrt(Π) −

<?php
echo "sqrt(pi) = " . sqrt(M_PI) . "\n";
echo "M_SQRTPI = " . M_SQRTPI. "\n";
echo "2/sqrt(pi) = " . 2/sqrt(M_PI) . "\n";
echo "M_2_SQRTPI = " . M_2_SQRTPI . "\n";
?>

## Output

This will produce following result −

sqrt(pi) = 1.7724538509055
M_SQRTPI = 1.7724538509055
2/sqrt(pi) = 1.1283791670955
M_2_SQRTPI = 1.1283791670955

## Example

Live Demo

sqrt(-1) is undefined hence it returns NAN

<?php
echo "sqrt(-1) = " . sqrt(-1) . "\n";
?>

## Output

This will produce following result −

sqrt(-1) = NAN