how to store each for loop values in multidimensional matrix?

Hello MATLAB Community,

I am finding a little problem to store values of each of the for loop iteration into a multi dimensional matrix.

below is my code:

zn = 3; % no. of planes

zmax = 200; % z max
zmin = 100; % z min

zA = linspace(zmax,zmin,zn); % linearly distributed z planes between z max & z min
phiA = (-180:180); % phi value from phi min to phi max
thetaA = (-180:180); % theta value from theta min to theta max

for zi = 1:length(zA)
    z = zA(zi);
    for phii = 1:length(phiA)
        phi = (phiA(phii));
        for thetai = 1:length(thetaA)
            theta = (thetaA(thetai));
            
            px = phi + theta;
            py = phi - theta;
            
            P = [px; py; z];
    
            if px>-30 && px<30 && py>-30 && py<30
                
                S(:,:,z) = P(:)';
            end
        end
    end
    
    fprintf('Processing %d of %d ...',zi,zn); % progress
    fprintf('done.\n'); % display when done
end

Since, I am creating 3 planes for this example. When I type S(:,:,3), I should be only able to store and access all the points (px & py) in that particular plane 3. Similarly S(:,:,2) should only store and access all points in plane 2,

but when I say S(:,:,z) I should be able to access & store all values of px & py of all planes.

But in my code, I am not able to do the above.

In my code, all values are being stored in multidimensional matrix and I am not able to differeiante the values according to the z planes.

Since number of planes are 3, there should be only 3 pages for the matrix 'S'.

Can anyone please help me with any suggestions.

Thank you in advance!!

I really appreciate your help.

Kind regards,

Shiv

Answer 1

[Simon Chan]

Try to use a cell array to store the result as follows:

zn = 3; % no. of planes
zmax = 200; % z max
zmin = 100; % z min
zA = linspace(zmax,zmin,zn); % linearly distributed z planes between z max & z min
phiA = (-180:180); % phi value from phi min to phi max
thetaA = (-180:180); % theta value from theta min to theta max
for zi = 1:length(zA)
    z = zA(zi);
    Pall = [];                                      % Initialize
    for phii = 1:length(phiA)
        phi = (phiA(phii));
        for thetai = 1:length(thetaA)
            theta = (thetaA(thetai));      
            px = phi + theta;
            py = phi - theta;           
            P = [px, py];                           % Store value for px and py only
            if px>-30 && px<30 && py>-30 && py<30
                Pall = [Pall;P];                    % Append the point which satisfy the condition 
            end
        end
    end
    S{zi} = Pall;                                   % Save into a cell array
    fprintf('Processing %d of %d ...',zi,zn); % progress
    fprintf('done.\n'); % display when done
end

Processing 1 of 3 ...

done.

Processing 2 of 3 ...

done.

Processing 3 of 3 ...

done.

S

S = 1×3 cell array
    {1741×2 double}    {1741×2 double}    {1741×2 double}

[Shiv Karpoor]

Hi Simon,

Thank you for the suggestion, storing in cell array actually worked on the real problem.

I appreciate your help!

Kind regards,

Shiv