[p, q] = get_products();

% quantity sum over a day
plot(sum(q'));

% plot prediction quallity
calc_error(q(29:42, :), mean_pred(q(1:28, :), 14));
calc_error(q(29:42, :), regress_pred(p, q(1:28, :)));
calc_error(q(29:42, :), repmat(sevenday_pred(q(1:28, :), 4), 2, 1));