MATLAB: How to find the derivative of a polynomial fit

derivativeplotting

Hello
I have to plot 4 different subplot with the data provided. I plotted 3 of them(original, polynomial fit and integral), but I have having a hard time finding the derivative of the polynomial fit and plotting it. How do I do this?
xcor =  ;% Some x value
ycor =  ;% Some y value
opol =  ;%order of polynomial
xx = polyfit(xcor,ycor, opol);
yy = polyval(xx, xcor);
plot(xcor, 'New derivative of polynomial fit')
How do I use the polynomial fit(xx) and the value of xor and ecru to plot the data?
Thank you.

Best Answer

For the derivative, I would use the polyder function.
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