PHP 5.6.16 is available

# sqrt

(PHP 4, PHP 5)

sqrt평방 제곱근

### 설명

float sqrt ( float `\$arg` )

`arg`의 평방제곱근을 반환합니다.

`arg`

계산할 인수

### 반환값

`arg`의 평방제곱근이나, 음수일 경우엔 특수 값 NAN.

### 예제

Example #1 sqrt() 예제

``` <?php// 정밀도는 precision 설정에 의존합니다.echo sqrt(9); // 3echo sqrt(10); // 3.16227766 ...?> ```

### 참고

• pow() - 거듭제곱 표현

``` 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;}?> ```