Hi, anybody can help me to check for question b whether my answer is correct or not? Thanks.

Here is my code:

t = [0:19];
y = [6,13,23,33,54,83,118,156,210,282,...
350,440,557,685,815,990,1170,1350,1575,1830];
length (y)
Yy=-316.66;
d=y-Yy;
figure(2), bar(t,d)
r2=1-sum(d.^2)/sum((y-mean(y)).^2)

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Answer 1

[Image Analyst]

My demo on polyfit is attached. It fits a line and a cubic. Adapt as needed for your problem.

Answer 2

[Image Analyst]

For example:

coefficients = polyfit(t, y, 2);
fprintf('The equation is y = %f*t^2 + %f*t + %f\n',...
    coefficients(1), coefficients(2), coefficients(3));
yfitted = polyval(coefficients, t);
sumOfResiduals = sum(.............  you finish it.