PHP 7.1.21 Released

# hypot

(PHP 4 >= 4.1.0, PHP 5, PHP 7)

hypot 计算一直角三角形的斜边长度

### 说明

float hypot ( float `\$x` , float `\$y` )

hypot() 函数将会跟据直角三角形的两直解边长度 `x``y` 计算其斜边的长度。或者是从标点 (`x`, `y`) 到原点的距离。该函数的算法等同于 sqrt(x*x + y*y)

`x`

`y`

### 返回值

``` If you need a higher-dimensional diagonal length (norm), you can exploit the fact that sqrt(x*x+y*y+z*z) == sqrt(x*x+sqrt(y*y+z*z)). In other words hypot(x, y, z)==hypot(x, hypot(y, z)).To be generic about it....<?phpfunction norm(...\$args){    return array_reduce(\$args, 'hypot', 0);}?> ```
``` A simpler approach would be to allow an arbitrary number of parameters. That would allow for whatever number of dimensions you want *and* it would be backwards compatible with the current implementation.<?phpfunction hypo() {    \$sum = 0;    foreach (func_get_args() as \$dimension) {        if (!is_numeric(\$dimension)) return -1;        \$sum += pow(\$dimension, 2);    }    return sqrt(\$sum);}print hypo();          // vector in 0 dimensions, magnitude = 0.print hypo(1);         // vector in 1 dimension,  magnitude = 1.print hypo(3, 4);       // vector in 2 dimensions, magnitude = 5.print hypo(2, 3, 6);     // vector in 3 dimensions, magnitude = 7.?> ```