# if mean("s", @array) is used
# then the array will be summed
# by the function. Otherwise,
# the usage is
# mean($sumOfValues, $numberOfValues);
#
sub mean {
my($action) = shift;

if ($action eq "s") {
my($sum) = 0;
my($count) = 0;

foreach (@_) {
$sum += $_;
$count++;
}
}
else {
my($sum, $count) = @_;
}
$sum / $count;
}