Polyfit Vs Fit command: what are the differences?

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PRB
PRB 2020-5-15
评论： PRB 2020-5-26
I would like to predict a quadratic curve (y=ax2 + bx + c) from a data set and the relative goodness of the fit model.
I used both the command polyfit (Polynomial curve fitting) and Fit (Fit the curve).
what is the difference between the two methods? Whit the second method I used 'normalize' but when I try to find the value with polyval the predicted data are no correct.
How can I test the goodness of the fit model if I use the command Poltyfit?
Thank you in advance

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Jyotsna Talluri
Jyotsna Talluri 2020-5-25
Refer the below link to know the differences betwween fit and polyfit
https://www.mathworks.com/matlabcentral/answers/81143-fit-and-polyfit-lar-vs-least-squares
We cannot determine the goodness of fit using polyfit.Use fit function to determine the goodness of fit.
[fitobject,gof] = fit(x,y,fitType)
returns goodness-of-fit in the structure gof.

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