MATLAB: Painting the area of difference between two lines

plot

I have a plot like the image. There are two occasions where the orange line is above the blue line (around 211 and 331 on the x-axis). I would like to paint the area between the two lines for the two occasions to highlight that the blue is below the orange.

Best Answer

I don’t have your data, so I created my own:
zci = @(v) find(v(:).*circshift(v(:), [-1 0]) <= 0);                    % Returns Zero-Crossing Indices Of Argument Vector
x = linspace(0, 100, 250);                                              % Independent Variable
y1 = exp(-0.05*x).*sin(2*pi*x/30);                                      % First Dependent Variable
y2 = 0.5*exp(-0.07*x).*sin(2*pi*x/20);                                  % Second Dependent Variable
yd = y1 - y2;                                                           % Difference (Use To Detect Zero-Crossings)
xc = zci(yd);                                                           % Zero Crossings
idxs = xc(2:2:end-1);                                                   % Start Indices Of Overlap
idxe = xc(3:2:end);                                                     % End Indices Of Overlap
figure(1)
plot(x, y1)
hold on
plot(x, y2)
for k1 = 1:size(idxs,1)
    fill([x(idxs(k1):idxe(k1)) fliplr(x(idxs(k1):idxe(k1)))], [y1(idxs(k1):idxe(k1)) fliplr(y2(idxs(k1):idxe(k1)))], 'g')
end
hold off
grid
You should be able to adapt it to your data with little or no alteration, although you might need to adjust ‘idxs’ and ‘idxe’.
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