Matlab 2018a fit function wrong coefficients

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avihai 2021-2-6

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评论： Star Strider 2021-2-9

Hi,

I tried to use the fit function for a rational fitting (rat24) and I got very strange results although the fitted curve was similar to my function.

So I tried to use it with a known function: y=2t and did the fitting and the output again was wrong.

So in the following example I expected p1=0 and p2=2 and I get different results.

What am I doing wrong?

Thanks,

Avihai

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James Tursa 2021-2-8

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Star Strider 2021-2-6

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The 'Normalize','on' name-value pair tells the function to centre and scale the data. This is appropriate for some situations where the independent variable does not begin at 0, and the dependent variable is much greater than 0. (To then plot it, that information must be included or the result will be significantly different from that expected.) Changing to 'Normalize','off', will produce the anticipated result for the parameter estimates.