How to fix the Dot indexing is not supported for variables of this type error?

clc;
clear all;
close all;
format long g;
load('dtm.mat')

dist_hwZ= repmat([0:100:(size(Z,1)-1)*100]',1,size(Z,2));
dist_rwZ = (repmat([0:100:(size(Z,2)-1)*100]',1,size(Z,1),1))';

thinned_dist_hwZ = dist_hwZ(1:5:end,1:5:end);
thinned_dist_rwZ = dist_rwZ(1:5:end,1:5:end);
% thinned_dist_rwZ = (thinned_dist_rwZ)';
thinned_Z = Z(1:5:end,1:5:end);

current_dist = NaN(size(thinned_dist_hwZ));
assigned_dist = current_dist;                %line23


for i = 1:length(thinned_dist_hwZ,1)
    for j=1:length(thinned_dist_hwZ,2)
       current_dist = sqrt(((thinned_dist_hwZ-thinned_dist_hwZ(i,j)).^2 + (thinned_dist_rwZ-thinned_dist_rwZ(i,j)).^2)');
       %compute distance not height     % sqrt delx^2 dely^2  approx 70 km distance of hypotenous 
                
if i==1 && j==1
    max_dist=max(max(current_dist));
end
        
        for k =1:round(max_dist/1e4)
            if k==1
                assigned_dist(current_dist<=k*1e4)=k;
            else
                assigned_dist(current_dist<=k*1e4 & current_dist>(k-1)*1e4)=k;
            end
            prod_Z = Z(assigned_dist==k).*Z(i,j);
            
            eval(['allClasses.i' num2str(i) ['.j' num2str(j) ['.k' num2str(k) '=prod_Z' ]]]);
                
            if k==1
                eval(['K1:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']); 
            elseif k==2
                eval(['K2:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                
            elseif k==3
                eval(['K3:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                  
            elseif k==4
                eval(['K4:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                 
             elseif k==5
                eval(['K5:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                 
            elseif k==6
                eval(['K6:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                 
            else
                eval(['K7:prod_Z_' [num2str(i) '_' num2str(j)] '=prod_Z']);                  
            end
        end
        imagesc(current_dist)
    end
end

fns = fieldnames(k);

[Stephen23]

"How to fix the Dot indexing is not supported for variables of this type error?"

Better code. Your design forces you into writing slow, inefficient, complex code which is liable to bugs and difficult to debug. This is exactly what you are facing now. You can avoid this by designing your data better and using more reliable and efficient code paradigms:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

For example, this line:

eval(['allClasses.i' num2str(i) ['.j' num2str(j) ['.k' num2str(k) '=prod_Z' ]]]);

what is the point in having these multiple nested horizontal concatenations? Why do you need superfluous EVAL when fieldnames can be specified directly?:

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html

Even better would be to avoid forcing meta-data into fieldnames (slow) and use arrays instead (fast, could be numeric or container class, e.g. structure). Bad code also makes it easy to hide bugs:

K7:prod_Z_1_1 = prod_Z
  ^ What do you expect this syntax to achieve?

Better data design allows for simpler, more efficient code, with fewer bugs.

Answer 1

[KSSV]

Replace (i.j) with (i,j). There is . (dot) between i and j; replace it with comma.

it seems a typo error.

[vimal kumar chawda]

Thanks , it has been corrected. But I am getting some more error as below

Arrays have incompatible sizes for this operation.

Related documentation

[KSSV]

The dimensions which you are subtracting are different. You have to transpose them to get into order for subtractions.

[vimal kumar chawda]

I have edited the code with update as per your comment but still

Error using length

Too many input arguments.

Where it is the problem? Can you please update me?

[KSSV]

REad the documentation of the respective function.

It should

length(thinned_dist_hwZ,1)

Replaced with

length(thinned_dist_hwZ)