function calc_error(name, data, pred)

	quad = quad_error(data, pred);
	total = total_error(data, pred);

	printf('%10s quad: %d\t total: %d\n', name, quad, total);

	plot((sum(abs(data - pred))), '-ob;unsorted;');
	hold on;
	plot(sort(sum(abs(data - pred))), '-or;sorted;');
	hold off;
	xlabel('products');
	ylabel('total error');
end