# polynomial regression of a given function

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Anas Gharsa on 25 Jan 2022
Commented: Anas Gharsa on 25 Jan 2022
i am trying to write a function which produces the regression polynomial of degree 2 for a given datapoints (x and f(x) where f is the function to be approximated). this is what i wrote !! the code gives me 0 errors but i can not plot the results for some reasons that i dont know
x=input('Enter the x coordinates');
y=input('Enter the y coordinates');
n=input('Enter the order of the polynomial');
coeff=polyfit(x,y,n);
p = polyfit(x,y,n);
plot p;

Jon on 25 Jan 2022
You only solved for the coefficients. If you want to compare the original data and the fit you can do something like this, after your code above (I assume the x values are entered in increasing order)
xfit = linspace(x(1),x(end))
yfit = polyval(p,xfit);
plot(x,y,'o',xfit,yfit,'-')
Anas Gharsa on 25 Jan 2022
Yes that's right!! i intend to enter the x values in increasing order!!! Thank you so much this is so helpful

R2021b

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