x=[4.12 1.77 2.48 4.80 3.61 2.67 6.59 3.30 5.02 3.21 4.61 5.81 4.67 4.63 5.91 5.91 6.10 7.99 6.62]y=[3 3 4 6 6 6 6 6 6 6 7 7 8 8 10 11 11 12 12]plot(x,y,'r')hold onp=polyfit(x,y,2)x1=linspace(min(x),max(x),100);y1=polyval(p,x1);plot(x1,y1)