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# hypot

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

hypot 直角三角形の斜辺の長さを計算する

### 説明

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

hypot() は、直角をはさむ 2 辺の長さが `x` および `y` である 直角三角形の斜辺の長さ、すなわち原点と (`x`, `y`) との距離を返します。 これは sqrt(x*x + y*y) と等価です。

`x`

`y`

### 返り値 add a note

### User Contributed Notes 2 notes

Hayley Watson
2 years ago
``` 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);}?> ```
-16
robinv at ecosse dot net
15 years ago
``` 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.?> ``` 