stats_harmonic_mean

(PECL stats >= 1.0.0)

stats_harmonic_mean — Returns the harmonic mean of an array of values

说明

stats_harmonic_mean ( array $a ) : number

Returns the harmonic mean of the values in a.

参数

a

The input array

返回值

Returns the harmonic mean of the values in a, or FALSE if a is empty or is not an array.

User Contributed Notes

Daniel Morris (www.danielxmorris.com) 15-Aug-2008 07:51
I wrote this to calculate harmonic averages in my shares program.  Hopefully this can help someone who doesn't want to use PECL.  The function accepts an unlimited number of arguments without the need to place them into an array, which is better than the way the PECL extension handles the function.

<?php

/**
 *  @author    Daniel Morris
*/
function harmonic () {
    $num_args = func_num_args ();
    for ($i = 0; $i < $num_args; $i++) {
        $sum += 1 / func_get_arg ($i);
    }
    return $num_args / $sum;
}

// Tests

echo harmonic (1, 2, 3, 4, 5);
echo harmonic (-1, 3, 4, 10293);
echo harmonic (-1, -2, -3, -4, -5);

//  2.1897810218978
//  -9.6022389365052
//  -2.1897810218978 

?>