# x-y plot: how to shade the difference between two lines in multiple colors

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MS on 23 Jul 2020
Commented: Star Strider on 24 Jul 2020
kindly help me to fill the diffrence with two diffrent colur in a x y plot as shown in the below example figure? I need to shade postive(red color) and negative diffrences(blue color) in diffrent colors. Kindly give your suggesttions t= 0:.01:1
AA = cos(t)
BB= sin(t)
diff = AA-BB
plot(t,AA)
hold on
plot(t,BB)
patch([t fliplr(t)], [AA fliplr(BB)], 'r')
hold off
%%% any suggestions Please!!

Star Strider on 24 Jul 2020
Correct idea, not quite the correct approach.
Try this:
t= 0:.01:1;
AA = cos(t);
BB= sin(t);
Lv = AA > BB; % Logical Vector
figure
plot(t,AA)
hold on
plot(t,BB)
patch([t(Lv) fliplr(t(Lv))], [AA(Lv) fliplr(BB(Lv))], 'r')
patch([t(~Lv) fliplr(t(~Lv))], [AA(~Lv) fliplr(BB(~Lv))], 'g')
hold off
producing: .This uses ‘logical indexing’ to separate the two regions.
The independent variable (‘t’ here) may need greater resolution for more complicated curves for this approach to work correctly. If the curves are data, use linspace to create the indpendent variable vector with greater resolution, and interp1 to interpolate the data to it.
Star Strider on 24 Jul 2020
As always, my pleasure!