# Find the local and global maxima and minima

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Priyadarshini Nair on 27 Oct 2021
Commented: Mahesh on 24 Dec 2022
Find the local and global maxima and minima for the function f(x)=sin|x|, in an interval I = (−2π, 2π)
Jaya on 27 Oct 2021
As anyway you have tagged this question under the tag homework with no sample code, I have tried providing a resource for you to read rather than soving it by myself!

Alamanda Ponappa Poovaya on 1 Nov 2021
One option is to use ‘findpeaks’ in the Signal Processing Toolbox. It will give you the maximum (and indirectly the minimum) values and their index locations. If ‘y’ is the vector that produced the plot, to find the maxima and minima:
n = -2*pi:0.01:2*pi;
y = sin(abs(n));
plot(n,y);
[Maxima,MaxIdx] = findpeaks(y);
%plot maxima
hold on;
plot(n(MaxIdx),Maxima,'r*');
[Minima,MinIdx] = findpeaks(-y);
%plot minima
plot(n(MinIdx),-Minima,'g*');
hold off;
This will plot the maxima in red and the minima in green. You can refer to the Maxima and Minima arrays to get the maximum and minimum values respectively
Refer to the documentation for findpeaks below:
Mahesh on 24 Dec 2022
How can we plot sine & cos at same time

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