hypot

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 和 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)。

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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.



?>

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