% Least sqaures polynomial fitting 
% Calculate a polynomial fit 
% enter x and y data
x = [1 2 3 4 5 6 7 8 9]';
y = [.9 2.4 2.8 2.1 2.7 3.6 4.2 4.4 5.1]';
X = [ones(size(x)) x x.^2 x.^3 x.^4 x.^5];  % the ones are used for the 
% constant (a0) term
a = X\y;  % solve using the Matlab backslash operator
% plot the data and polynomial
T = [0:0.1:10]';
Y = [ones(size(T)) T T.^2 T.^3 T.^4 T.^5 ]*a;
plot(T,Y,'-',x,y,'or')
title('2nd degree polynomial least squares fit ')
xlabel('x')
ylabel('y')
pause
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% now perform the same calculations with polyfit
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% standardi