Matlab- solving odes for a matrix

[birdhen]

Hi there,

I have yet another Matlab query.
I have an m=file that I am using to solve an ode.
This file has a constant (call it H) within the differential and when I use the ode solver in the command window returns values of z and r (this returns two 85x1 vectors which can be plotted against each other).
Now I want to make H vary between 4200 and 4400 and get 85 values of z and r for every step in H, i.e. I want to get a matrix of 85x200 for each of z and r.
I am sorry if this is not worded very well, I am a bit confused as I am a Matlab novice, if anyone could give me some tips that would be much appreciated.

Cheers

 

[Aaron Bex]

To do this, you will need to create a loop that takes the value of H and runs the ode solver with each value of H. The code should look something like this:

for i = 4200:4400
% Set value of H
H = i;

% Run ode solver
[z, r] = ode45(@your_ode_file, tspan, y0);

% Save results
z_results(:,i) = z;
r_results(:,i) = r;
end

Once the loop is complete, you can access the results in the matrices z_results and r_results.

Hope that helps!

 

[oswaler]

I would suggest using a for loop to vary the value of H and store the resulting z and r values in a matrix. This can be achieved by creating a vector of values for H (e.g. H = 4200:1:4400) and then using a for loop to iterate through each value of H. Within the loop, you can use the ode solver to solve for z and r and store them in a matrix using indexing. For example, if your matrix for z and r is called "zr_matrix", the code within the loop could look something like this:

for i = 1:length(H)
% solve ode for z and r using H(i)
[z, r] = ode_solver(H(i));

% store z and r values in matrix
zr_matrix(:,i) = [z r];
end

This will result in a matrix with 85 rows and 200 columns, where each column represents the z and r values for a specific value of H. I hope this helps and feel free to reach out if you have any further questions.