MATLAB plot of data (spectro) with maximum indicator

load llspectro6.txt
x = llspectro6 (:,1);
y = llspectro6 (:,2);
[Peak, PeakIdx] = findpeaks(y);
plot(x,y, 'cyan', 'Linewidth', 2)
ylabel ('Intensity (Counts)')
xlabel ('Wavelength (nm)')
indexmin = find(min(y) == y);
xmin = x(indexmin);
ymin = y(indexmin);
indexmax = find(max(y) == y);
xmax = x(indexmax);
ymax = y(indexmax);
strmax = ['Maximum = ',num2str(xmax)];
text(xmax,ymax,strmax,'HorizontalAlignment','right');