$rate_win = PDL::Graphics::PGPLOT::Window->new(Device => '/xw',
            Aspect => 1, WindowWidth => 5, NXPanel => 2);

$area_win = PDL::Graphics::PGPLOT::Window->new(Device => '/xw',
            Aspect => 1, WindowWidth => 5);

$rate_win->env(0, 10, 0, 1000, {XTitle => 'Days', YTitle => '#Rabbits'});
$rate_win->env(0, 10, 0, 100, {Xtitle=>'Days', Ytitle => 'Rabbits/day'});

$area_win->env(0, 1, 0, 1, {XTitle => 'Km', Ytitle => 'Km'});
# And theoretical prediction.
$rate_win->line(sequence(10), fibonacci(10), {Panel => [1, 1]});