함수 geomean()

GEOMEAN

array_geomean

1 Excel

=GEOMEAN(1,2,3,4,5)
// 2.605171085

=GEOMEAN(4,5,8,7,11,4,3)
// 5.47698697

=GEOMEAN(-1,3,4,10293)
// #NUM!

=GEOMEAN(-1,-2,-3,-4,-5)
// #NUM!

2 PHP

function array_geomean($a) {  
   foreach($a as $i=>$n) $mul = $i == 0 ? $n : $mul*$n;  
   return pow($mul,1/count($a));  
}

echo array_geomean( array(1, 2, 3, 4, 5) );
// 2.6051710846974
echo array_geomean( array(4, 5, 8, 7, 11, 4, 3) );
// 5.476986969657
echo array_geomean( array(-1, 3, 4, 10293) );
// NAN
echo array_geomean( array(-1, -2, -3, -4, -5) );
// NAN

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