preg_grep

// return all array elements
// containing floating point numbers
$array = array(120, 256.2, 985, 254, 654, 85.24, 65.9, 87);
$fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);

print_r($fl_array);

Array
(
    [1] => 256.2
    [5] => 85.24
    [6] => 65.9
)