write equation in for loop

I have to update this equation

• Pij^(k+1)=[Pij^k-a^k*(xij^k-yij^k)]+

where i represents row, j represents coloumn and k represents the iteration.

How to write this equation in for loop

Answer 1

[Voss]

If you want to overwrite the values of a, x, y, and P on each iteration, then maybe you can do this:

P = P-a*(x-y);

If instead you want to store the values of a, x, y, and P for each iteration, then maybe it would be something like this:

P(:,:,k+1) = P(:,:,k)-a(k)*(x(:,:,k)-y(:,:,k));

or perhaps this:

P{k+1} = P{k}-a(k)*(x{k}-y{k});

depending on whether the sizes of P, x, and y might change with each iteration.

[Ancy S G]

Ok.thank you.

But I have to change the i,j along with each iteration.If a 3*2 matrix is considered,then I want P11^(k+1),P12^(k+1), upto P32^(k+1) and if Pij^(k+1)-Pij^(k)>0.1,then go for next iteration. How it is possible in for loop?

[Voss]

The notation in my answer (the MATLAB syntax) uses all elements of P. In other words, it uses all i,j.

You can apply the condition that Pij^(k+1)-Pij^(k)>0.1 to each individual element of P in a couple of different ways, depending on (Case 1) whether the each element should stop being updated when the condition is no longer met for that element, or (Case 2) whether they all should stop being updated only when the condition is no longer met in all elements.

In either case, the condition can be used to iterate in a while loop like this:

while any(any(P(:,:,k+1)-P(:,:,k) > 0.1))
    % do another iteration
end

and then the code within the while loop will update a and x, y either at all elements or only some depending on how you write it.