MATLAB: Highlight a Section of a Plot

plots

I would like to insert a vertical bar (light blue) from Time = 500 to Time = 650 to highlight that section of the curve. I believe patch is the tool to use. I followed examples provided on MathWorks, but my curve disappears when I use the recommended code. How can I incorporate patch into the code below?
plot(t,B);
xlabel('Time (in days)');
ylabel('Mosquitoes Searching for a Blood Meal');
h_xlabel = get(gca,'XLabel');
set(h_xlabel,'FontSize',14);
h_ylabel = get(gca,'YLabel');
set(h_ylabel,'FontSize',14);
set(gca,'fontName','Helvetica');
hold on;
I know that I should use patch before plotting my curve so that the vertical bar does not cover the curve.

Best Answer

Try this:
t = linspace(350, 750);                                             % Create Data

y = sin(2*pi*t/200 + 2) .* cos(2*pi*t/300)*0.2 + 0.2;               % Create Data
ptchidx = (t >= 500) & (t <= 650);                                  % Area To Shade
figure(1)
plot(t, y)
hold on
patch([t(ptchidx) fliplr(t(ptchidx))], [y(ptchidx) zeros(size(y(ptchidx)))], [0.6 0.4 0.9], 'FaceAlpha',0.3, 'EdgeColor','none')
hold off
grid
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