MATLAB: Nested loop results in 3d matrix and plot3

3d matrixmesh

I am trying to run a nested loop to get three values saved as 3d matrix and then get a 3d plot from them. How can I do this. The values come from Xi+1 = r*Xi(1 − Xi), where i range from 1:50 and r from 2.4 to 4.
###Code####
r=2.4:0.1:4;
for j=1:16;
    X(1,1)=.5;
    xsav(1,1)=1;
    xsav(1,2)=X(1);
    r(j)=2.4+j*.1;
    for i=1:50;
        X(i+1)=r(j)*X(i)*(1-X(i));
    end
end
How do I save these values and plot a 3d. (mesh or plot3 or comet3)

Best Answer

Rajeev - why does your code define r as
 r=2.4:0.1:4;
and then overwrite the jth element on each iteration of the outer for loop with
 r(j)=2.4+j*.1;
This shouldn't be necessary since you have already defined r. As for saving the data to X, you can get a two-dimensional matrix/array as
 r=2.4:0.1:4;
 X = zeros(50,length(r));
 for j=1:length(r)
    X(1,j)=.5;
    for i=1:size(X,1)-1
        X(i+1,j)=r(j)*X(i,j)*(1-X(i,j));
    end
 end
In this case, X will be a 50x17 matrix. It isn't clear to me how you expect to get a 3D matrix from the above code, so please clarify.
As an aside, using i and j as your indexing variables is generally discouraged since MATLAB uses both to represent the imaginary number.
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