The 5th Annual China PHP Conference

# sqrt

(PHP 4, PHP 5)

sqrtریشه مربعی

### Description

float sqrt ( float \$arg )

بازگرداندن ریشه مربع arg.

### Parameters

arg

آرگومان برای پردازش

### Return Values

ریشه مربع arg با مقدار ویژه NAN برای عدد منفی.

### Examples

Example #1 sqrt() example

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

• pow() - Exponential expression

``` 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 ```
``` 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.<?phplist(\$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;}?> ```