Science:Math Exam Resources/Courses/MATH307/April 2012/Question 05 (c)

MATH307 April 2012

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Question 05 (c)

You are given a set of 100 data points (xn, yn) with xn increasing. (c) Suppose instead that you choose to make a least square fit of the data points to a quadratic polynomial $\displaystyle f(x)=c_{0}x^{2}+c_{1}x+c_{2}.$ Write down the MATLAB/Octave command you would use to calculate the coefficients, plot the original data points and plot the quadratic fit (you may assume that vectors $X=[x_{1},x_{2},\dots ,x_{N}]^{T}$ and $Y=[y_{1},y_{2},\dots ,y_{N}]^{T}$ have already been defined).

Make sure you understand the problem fully: What is the question asking you to do? Are there specific conditions or constraints that you should take note of? How will you know if your answer is correct from your work only? Can you rephrase the question in your own words in a way that makes sense to you?

If you are stuck, check the hint below. Consider it for a while. Does it give you a new idea on how to approach the problem? If so, try it!

Hint

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Solution
Found a typo? Is this solution unclear? Let us know here. Please rate my easiness! It's quick and helps everyone guide their studies. A= ones(100,1) for n=1:99 A=[X.^n A]; end a= A'*A\A'*Y plot(X,Y,'or') hold on XX=linspace(X(1),X(100),1000); plot(XX,a(1)*XX.^2+a(2)*XX=C3*ones(1,length(XX)))

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