clear all; close all;
c3 = [0.74  0.97 1.1  0.86];
x=-1:0.1:1;
y=polyval(c3,x)
noise=randn(1,size(y,2) );
noise=noise/norm(noise);
ey= y + noise;
ec=polyfit(x,ey,3);
hold on
plot(x,y,'b--' );
plot(x,ey,'r+');
fy=polyval(ec,x);
plot(x,fy,'g');