hypot

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

hypot 计算一直角三角形的斜边长度

说明

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

hypot() 函数将会跟据直角三角形的两直解边长度 xy 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

-7
Hayley Watson
4 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)).

<?php

function norm(...\$args)
{
return
array_reduce(\$args, 'hypot', 0);
}

?>
-19
robinv at ecosse dot net
18 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.

<?php

function 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.

?> 