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?

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".

[KALYAN ACHARJYA]

Can you share the plots figure? or similar representation code

[Saraswatula Sai Pavan Sastry Sastry SOME]

[KALYAN ACHARJYA]

Here 4 plots, which two plots?

[Saraswatula Sai Pavan Sastry Sastry SOME]

4 plots..? I didn't get you? DIFFERENCE BETWEEN THE PINK AND BLUE CURVES ...THAT ALL THAT I NEED? HELP ME FIND IT. THANK YOU

Answer 1

[KALYAN ACHARJYA]

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;

[Saraswatula Sai Pavan Sastry Sastry SOME]

Thanks, but I don't find this answer as solution to my problem.

Answer 2

[Image Analyst]

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.

[Saraswatula Sai Pavan Sastry Sastry SOME]

For my experimental data I can't define a relation i.e between the x2 and y2.