polynomial help, is it to simply just use polyfit? I cant figure it out, I don't use matlab regularly

[John D'Errico]

Please stop posting your homwework problems with no effort made. Answers is not a service where we do your homework for you.

[Chad Parker]

I'm not asking for you or anyone to solve the problem, I am requesting help/guidance. Simply helping my by providing the hyperlink to the pages to help would suffice, why were the others able to be helpful and you are quick to reject. Don't worry I won't ask any more questions on this page. Appreciate "your" help.

Answer 1

[Image Analyst]

Hint

Put this in a loop where you increase the order

coefficients = polyfit(x, y, order);
estimatedy = polyval(coefficients, x);
plot(x, y, 'r.', 'MarkerSize', 10);
mse(order) = sum((estimatedy - y).^2)
figure;
plot(mse, 'b-', 'LineWidth', 2)
grid on;

[Chad Parker]

like this?

for order = 1:10;

coefficients = polyfit(x, y, order);

estimatedy = polyval(coefficients, x);

plot(x, y, 'r.', 'MarkerSize', 10);

grid on;

mse(order) = sum((estimatedy - y).^2);

end

figure;

plot(mse, 'b-', 'LineWidth', 2)

grid on;

[Image Analyst]

Yeah, pretty close. I'd just make a few changes but that would be just to make the plots prettier.

Answer 2

[Matt J]

Yes, you could do most of it with polyfit.

[Chad Parker]

would it be polyfit(x,y,10) and the output is the residual sums of squares?

[Torsten]

https://de.mathworks.com/help/matlab/ref/polyfit.html

[Chad Parker]

I found that polyfit page, but am I missing something? Maybe I am overthinking it, would it be polyfit(x,y,10)? and that is all the questions is asking? and maybe to plot?

[Sam Chak]

@Chad Parker

I think the assignment requires you to fit the data points with polynomials from the 1st-degree to the 10th-degree, if I'm not mistaken.

p01 = polyfit(x, y, 1);
p02 = polyfit(x, y, 2);
p03 = polyfit(x, y, 3);
p04 = polyfit(x, y, 4);
p05 = polyfit(x, y, 5);
p06 = polyfit(x, y, 6);
p07 = polyfit(x, y, 7);
p08 = polyfit(x, y, 8);
p09 = polyfit(x, y, 9);
p10 = polyfit(x, y, 10);