Contour not plotting correctly in MATLAB--works in Mathematica
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Emma Reznick
on 19 Mar 2018
Commented: Abraham Boayue
on 20 Mar 2018
I've been trying to get a contour to plot in MATLAB where I have been running analysis on my data, but it will not plot correctly. I have translated the formula into Mathematica (just get rid of all of the matrix '.' operations) and it plots correctly (below).
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/171390/image.jpeg)
This is the formula that it should be plotting:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/171391/image.jpeg)
And this is the code I have been running on MATLAB to no avail (it seems to scale with S and F input ranges):
%Establish Constants from Literature
s_u = 1.202^2;
f_u = (168/60)^2;
E0 = 24/60;
%Generate Matricies
f = linspace(0,1);
s = linspace(0,2.5);
[S,F] = meshgrid(s,f);
Z = ((s_u)*(f_u)*E0)./(S.*F.* (s_u-(S.^2)).* (f_u-(F.^2)) );
%Plot
contour(F,S,Z)
Any help would be much appreciated!
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Accepted Answer
Abraham Boayue
on 20 Mar 2018
Hey Emma, what happens if you divide by zero, looks like you are doing just that (S and F will become zero at some point in your code). This is not a solution. It's just to allow you see clearly what's going on in the background of your code.
%Generate Matricies (Increase the figure window to see clearly)
f = linspace(-30,20, 30); % some combinations of f and s will include zero
s = linspace(-20,20,30); % in S or F giving an undesirable result, since division
% by zero is not allowed.
[S,F] = meshgrid(s,f);
ss = find(S==0); % Check for zeros in S and F
ff = find(F==0); % Try to make some conditions to avoid dividing by zero.
Z = ((s_u)*(f_u)*E0)./(S.*F.* (s_u-(S.^2)).* (f_u-(F.^2)) );
%Plot
Zmin = min(min(Z));
Zmax = max(max(Z));
spacing = 0.005; % draw more circles between each interval for smaller values
topspace = 1; % increase the upper limit circles
levels=[Zmin:spacing:1,1,1:topspace:Zmax];
contour(F,S,Z,levels);
grid
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