for (@_) { @differences = (@differences, (($_-$mean)*($_-$mean))); }

##</code><code>##

  foreach ( @_ ) {
      push @differences, $_ - $mean;
  }

##</code><code>##

   my $standard = 0;
   for (@differences) { $standard = $standard + $_; }
   $standard = sqrt($standard/$sample_size);
   return $standard;

##</code><code>##

  my $sum_diff = 0;
  map { $sum_diff += $_ } @differences;
  return sqrt($sum_diff / $sample_size);