연평균 증가율 > PHP

function geomean() {
 $args = func_get_args();
 $m = 1;
 foreach($args as $n) $m *= $n;
 return pow($m,1/count($args));
}

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

function array_geomean($arr) {
 $m = 1;
 foreach($arr as $n) $m *= $n; 
 return pow($m,1/count($arr));
}

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