In terms of the basic arrangement, I'd approach it like this:

#some values to use
my @items = qw(oranges apples pears lemons kumquats);
#sort 'em
@items = sort @items;

# we want to output, e.g.
# A | D
# B | E
# C |
# so we need the offset for D,
#and a kludge to avoid warning on non-existent array elem. when printi
+ng odd num of items
my $item_count = @items;
my $offset  = int(($item_count+1)/2);
push @items, '';

map{
  print "$items[$_] | $items[$_ + $offset]\n";
}0..($offset-1);
[download]

map{$a=1-$_/10;map{$d=$a;$e=$b=$_/20-2;map{($d,$e)=(2*$d*$e+$a,$e**2
-$d**2+$b);$c=$d**2+$e**2>4?$d=8:_}1..50;print$c}0..59;print$/}0..20
[download]