hypot

(PHP 4 >= 4.1.0, PHP 5)

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 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)


add a note add a note User Contributed Notes
</Life>.org
10-Aug-2006 05:56
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)))
...
R. Victor Klassen
24-Jun-2005 11:03
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 01:18
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.

?>