How to add the strings in three for loops

what I want is to add 9terms(all k & m) for each i(1:3). h_1, h_2, h_3 each will have 9 additive terms. Example, h_1= h_1_1_1*a_1*b_1+ h_1_1_2*a_1*b_2+.......+h_1_3_3*a_3*b_3.

Thanks in advance.

ht=cell(3);
for i=1:3
    for k=1:3
        for m=1:3
            code2=['h_',num2str(i),'=h_',num2str(i),'_',num2str(k),'_',num2str(m),'*a_',num2str(k),'*b_',num2str(m)];
            ht{i}=strcat(ht,'+',code2) 
            eval(ht(i));          
        end
   end 
disp(ht(i));
end

[Stephen23]

Indexing would be much simpler and much more efficient.

The MATLAB documentation specifically warns against going exactly what you are trying to do: "A frequent use of the eval function is to create sets of variables such as A1, A2, ..., An, but this approach does not use the array processing power of MATLAB and is not recommended. The preferred method is to store related data in a single array."

source: https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

Magically accessing variable names is one way that beginners force themselves into writing slow, complex, buggy code that is hard to debug:

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

Answer 1

[Naman Chaturvedi]

Correct code:

ht=cell(3,1);
for i=1:3
    for k=1:3
        for m=1:3
            if (k*m==1)
                code2=['h_',num2str(i),'=h_',num2str(i),'_',num2str(k),'_',num2str(m),'*a_',num2str(k),'*b_',num2str(m)];
                ht{i}=[ht{i},code2];
            else
                code2=['h_',num2str(i),'_',num2str(k),'_',num2str(m),'*a_',num2str(k),'*b_',num2str(m)];
                ht{i}=[ht{i},'+',code2]; 
            end   
        end
     end 
disp(ht(i));
end

[Mahmuda Ishrat Malek]

Thank You but I ended up with a lot more complex code :(

[Stephen23]

"...but I ended up with a lot more complex code"

That is because your approach is very complex. Indexing would be much simpler, and much more efficient.

[Mahmuda Ishrat Malek]

Can you give a short example on how I can do this sort of thing with indexing?