PHP sqrt() function

Definition and usage

sqrt()The function returns the square root of a positive floating point number. Since the square root of a negative number is undefined, it returns NAN. This is one of the most commonly used functions.

This function always returns a floating point number.

Syntax

sqrt ( float $arg ) : float

Parameters

Serial number	Parameters and description
1	arg The number whose square root is required

Return value

PHP sqrt() function returns the square root of the given arg number. For negative numbers, the function returns NAN.

PHP Version

This function is available in PHP 4.x, PHP 5.x and PHP 7.x versions.

Example

Online Demonstration

The following example calculates the square root of 100−

<?php
   $arg = 100;
   echo "Square root of " . $arg . "=" . sqrt($arg) . "</p><p>";
?>

Output

This will produce the following result−

Square root of 100=10

Example

Demonstration

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

Output

This will produce the following results −

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

Example

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

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

Output

This will produce the following −

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

Example

Demonstration

sqrt(-1) is undefined and therefore returns NAN

<?php
   echo "sqrt(-1) = " . sqrt(-1) . "</p><p>";
?>

output

This will produce the following result−

sqrt(-1) = NAN

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