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matlab, please help

I'm trying to do the polynomial curve-fitting part of this pdf (attached). I'm having trouble calculating the coefficients. I get no 0th order coefficient. I'm also having a lot of trouble with the ' \ ' operator because even when the length of v and A match up (or should do) it says the matrix size is wrong.

This is my code


function[] = C002v2_2() 
    start = 0;
        fin = 200; 
     n = 100; 
     div = (fin - start)/n; 
     c1 = [1.5, -2.5, 0.7, -1.2]; 
    e = 0.01; 
    x = start:div:fin; 
    y = x; 
    for i = 1:n 
        y(i) = c1(1) + c1(2) * x(i) + c1(3) * x(i)^2 + c1(4) * x(i)^3 + e * randn(); 
    end
            v = zeros(4,1); 
    for k = 1:4 
        for i = 1:n 
            v(k) = v(k) + y(i)*x(i)^k; 
        end 
    end 
    A = zeros(4, 3); 
    for k = 1:4 
        for i = 1:3 
            for j = 1:n 
                A(k,i) = A(k,i) + x(j)^(i+k); 
            end 
        end 
    end 
        %A 
     %v 
            c2 = A \ v; 
     %c2
    yf = c2(1) + c2(2) * x + c2(3) * x.^2 + c2(4) * x.^3; 
    f = figure(); 
    plot(x, y, x, yf); 
end

Thanks so much. I'm desperate.

(edited 8 years ago)

C002.pdf192.7KB

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matlab, please help

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