fitting a polynomial function to data points and ploting it

Hi all

I want to fit a quadratic function to a data serie in MATLAB and calculate determination coefficient (R2) as well as quadratic equation.so desired outputs are as below: - scatter plot of data serie i.e. (x, y) - plot of quadratic fitting - quadratic equation - determination coefficient (R2) Could you please guide me. thanks

Answer 1

[Richard Willey]

If you have Curve Fitting Toolbox, you can generate everything you need as follows

X = 1:100;
X = X';
Y = X.^2 + 3*X + 5 + randn(100,1);

[foo Gof] = fit(X,Y, 'poly2')

scatter(X,Y)
hold on
plot(foo)

Answer 2

[Pawel Blaszczyk]

doc polyfit
doc polyval

I think this two function will be enoguh :)