CoderCruise

# sqrt

(PHP 4, PHP 5, PHP 7)

sqrtSquare root

### Description

float sqrt ( float \$arg )

Returns the square root of arg.

### Parameters

arg

The argument to process

### Return Values

The square root of arg or the special value NAN for negative numbers.

### Examples

Example #1 sqrt() example

<?php
// Precision depends on your precision directive
echo sqrt(9); // 3
echo sqrt(10); // 3.16227766 ...
?>

• pow() - Exponential expression

### User Contributed Notes 2 notes

10
jouhni at web dot de
11 years ago
To get any root of a number your can use the pow() function:

pow(8, 1/3)

which gives you the third root of eight.

Jouhni
-4
justin at hoogs dot com dot au
1 year ago
As we all know, the square of the hypotenuse is equal to the sum of the squares of the other two sides of a right triangle (a2 + b2 = c2).

With that in mind I created a quick way to reduce images to a maximum area without messing up width/height constraints.

<?php
list(\$width_orig, \$height_orig) = getimagesize(\$img);

\$max_a = 500000; // maximum area in pixels

\$width = \$width_orig;
\$height = \$height_orig;

\$area = \$width * \$height;
if (
\$area > \$max_a) {

\$mult = sqrt(\$max_a) / sqrt(\$height * \$width);

\$width *= \$mult;

\$height *= \$mult;
}
?>