to robinv at ecosse dot net:
hypo(a, b, c) === hypo(a, hypo(b, c))
hypo(a, b, c, d) === hypo(a, hypo(b, hypo(c, d)))
...
hypot
(PHP 4 >= 4.0.7, PHP 5)
hypot — 直角三角形の斜辺の長さを計算する
説明
float hypot
( float $x
, float $y
)
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。
パラメータ
- x
-
最初の辺の長さ。
- y
-
二番目の辺の長さ。
返り値
斜辺の長さを返します。
hypot
</Life>.org
10-Aug-2006 06:56
10-Aug-2006 06:56
R. Victor Klassen
25-Jun-2005 12:03
25-Jun-2005 12:03
A correct implementation of hypot( x, y ) avoids the overflow that might otherwise happen if either x or y is large enough that when squared it would overflow, but the answer is small enough not to cause overflow.
robinv at ecosse dot net
08-Jan-2004 02:18
08-Jan-2004 02:18
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.
?>