Find max value in polyfit

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rockstar49
rockstar49 on 20 Sep 2022
Edited: Matt J on 20 Sep 2022
Like to find the max value of this polyfit
tmp1=abs(FRF);
q1 = polyfit(f(f>0 & f <50),tmp1(f>0 & f <50),4);
z1 = polyval(q1,f);
plot(f(f>0 & f <50),z1(f>0 & f <50))

Answers (1)

Matt J
Matt J on 20 Sep 2022
Edited: Matt J on 20 Sep 2022
xcrit=roots(polyder(q1)); %set derivatives to 0
xcrit(imag(xcrit)~=0)=[]; %get rid of non-real solutions
zmax=max( polyval(q1, [0,xcrit',50]) ); %take max over critical points.
  3 Comments
Matt J
Matt J on 20 Sep 2022
Moved: Matt J on 20 Sep 2022
Yes, I fixed it.

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