HELLO.I need to find the difference between two plots in the same graph(deviation between model and experiment) and find the deviation between them. Can anyone please me how to do this?

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Saraswatula Sai Pavan Sastry Sastry SOME
评论： Saraswatula Sai Pavan Sastry Sastry SOME 2018-9-25
I have tried to take in points from the graph using digitializer but the array of points obtained from the respective plots seem to be of unequal size. So when I find the difference there is an error "matrix dimensions must agree".
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KALYAN ACHARJYA
KALYAN ACHARJYA 2018-9-23
For Difference, vector sizes must be the same. You can do the sorts of interpolation to make the both vectors having same size.
t=0:.1:10;
y1=sin(t);
plot(y1);
hold on;
y2=exp(t);
plot(y2);
y3=y1-y2;
plot(y3);
legend('sin(t)','exp(t)','y3(diff)');
hold off;
Image Analyst
Image Analyst 2018-9-23
编辑：Image Analyst 2018-9-23
This should do it. It works by getting a common x axis that has all the x coordinates from BOTH sets of your coordinates, i.e., by combining x1 and x2. Then it gets new y values by adding in, through interpolation, the y values from that set at the newly added x values from the other set of coordinates.
% Get the first set of data. Just use random coordinates for this demo.
n1 = 10
x1 = sort(rand(1, n1), 'ascend');
y1 = rand(1, n1);
% Get the second set of data. Just use random coordinates for this demo.
n2 = 15
x2 = sort(rand(1, n2), 'ascend');
y2 = rand(1, n2);
% Now we have our data and we can begin.
% Get the length of the first set of data.
length1 = length(x1);
% Get the length of the second set of data.
length2 = length(x2);
% Merge the two x axes.
x = sort([x1, x2], 'ascend');
% Get new y1 values by interpolating the y value
% at the newly added x2 coordinates
y1New = interp1(x1, y1, x);
% Get new y2 values by interpolating the y value
% at the newly added x1 coordinates
y2New = interp1(x2, y2, x);
% Plot things:
plot(x1, y1, 'rd-', 'LineWidth', 14);
hold on;
plot(x2, y2, 'bo-', 'LineWidth', 14);
plot(x, y1New, 'm*-', 'LineWidth', 2);
plot(x, y2New, 'c*-', 'LineWidth', 2);
legend('Set 1', 'Set2', 'Interpolated set 1', 'Interpolated set 2');
grid on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
Then, now that they have a common x, you can just compute the difference as y2New-y1New or whatever you want.

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