clear
clc
close all

y = [1 2 2.2 3 2.8 4.5 5 8 9];
x = 1:length(y);
x1 = 1:.1:length(y);
for order = 1:4
    coeff = polyfit(x, y, order);
    subplot(2, 2, order)
    plot(x, y,'r+')
    hold on
    y1 = polyval(coeff, x1);
    plot(x1, y1)
end