C code for polyfit

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Aziz 2014-5-25

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https://ww2.mathworks.cn/matlabcentral/answers/131081-c-code-for-polyfit

评论： Ryan Livingston 2014-5-28

1) In the matlab code below, I was expecting that when I generate code, it would give me C code for the polyfit function but it did not. Can you please tell me why? Is there any way for it to give me the C code for polyfit solving for the coefficients for the second order equation below?

function y = fcn(u) %#codegen

x = [100, 300, 500]; y = [0.0019, 0.000967, 0.00067]; z = polyfit (x,y, 2); y = z*100000; u = 1;

end

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dpb 2014-5-25

...but it did not. [expand to standalone C] Can you please tell me why?

'Cuz polyfit uses much intelligence in solving the system as it is general for any polynomial, not just linear or quadratic. That means a matrix inversion (in effect, not in reality) routine, etc., etc., etc., ...

If you needs must have it in C, probably shortest route is to derive the solution from the sums of squares terms specifically for the quadratic form and backsolve them.