# Formula basic fitting curve Matlab

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Dion Theunissen on 7 Jul 2021
Commented: LO on 7 Jul 2021
Hi,
I am using the equation from the basic fitting function from matlab. I am using the cubic equation.
Is there a way to figure out how this equation is calculated? What is the formula to calculate p1 untill p4?

LO on 7 Jul 2021
This is an excerpt from the help page of the interactive fitting function you are using:
The polyfit function performs the transformation itself if you provide three return arguments when calling it:
[p,S,mu] = polyfit(x,y,n)
The returned regression parameters, p, now are based on normalized x. The returned vector, mu, contains the mean and standard deviation of x. For more information, see the polyfit reference page.
https://de.mathworks.com/help/matlab/ref/polyfit.html
##### 2 CommentsShow NoneHide None
Dion Theunissen on 7 Jul 2021
Do you also know which parameter is used on which place? like p1 is normalized x, p2 is mu p3 is.... p4 is ....?
I want to include this formula in a script which will be calculated automaticly
LO on 7 Jul 2021
well this you could test by using known values of x and y, or try typing "help polyfit"
if you type "open polyfit" you will see the function code.
hope it helps

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