for loop index variable change inside the loop[

I have a very basic coding question but little tricky . Any help would be appreciated

The question follows :

a = [ 3 7 2 6]
x = large size vector 
for i = a
    for j = x(a,:)
        ... expression 
            .. expression
        
        c = find (a > j)
        if c ~0
            a (c )= a (c) -1;
        end
    end
end

But for loop index i not changing according to change in variable a. As i came to know from mathwork community it can't be changes . Could some one assit me how to approach this problem.

[KSSV]

Why don't you show us what you expect with a small example with data?

[Simon Chan]

Sample data can help a lot, below is what I guess:

Na = length(a);
for i = 1:Na
    value_a = a(i);                     % Get the value from matrix a one by one
    row_X = X(value_a,:);               % Extract the row from matrix X based on row number a
    c = find (value_a > row_X);
    if c ~=0
        row_X(c)= row_X(c)-1;           % Modify the matrix X after comparison
    end
end

[RAKESH KUMAR TOTA]

Sure .

a = [ 3 7 2 6]

let us suppose x = [ ] 10*4 size vector where array 'a' each cell are row position of x

for i = a

for j = x(a,:)

x(i,:) = []

c = find (a > j)

if c ~0

a (c )= a (c) -1;

end

end

end

Actually the data is too large to put it here.

If you need more specific then i have to thing and frame a small example. Anyway please let me know if you need more .

Thank you for your prompt response

[RAKESH KUMAR TOTA]

Thank you it served purpose how to accpet both answers @KSSV and @Simon Chan

[Rik]

Your comment is a bit confusing to me. Did KSSV and Simon solve the problem for you? They posted comments (not answers), so you can't mark them as accepted answer.

Answer 1

[Rik]

Once a for loop has started you can no longer change the expression it is based on.

You will have to rewrite your for loop as a while loop.