Problem with a for loop?

Hello i want to write a for loop inside another for loop .

I drew this as an example to make it easier to understand.

My idea was to code something like this but it didnt work:

%%%%

for a = 1:200

for b = 1:7200

Calc(b,a) = (Array1(b) * Array2(b,a)) + (Array1(b-1) * Array2(b-1,a-1));

end

Table(b,a) = Calc(b,a) / constant;

end

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I would be very grateful if someone could help .

Thanks in advance.

[Julian]

In your code is Calc, Table and Array of the dimension 7200x200 but in your picture 200x7200.

[malik abdelli]

yes thank you i just corrected it

[Julian]

But now your Array1 is also a 7200x200 matrix, then you would have to initialize that differently too.

Should you "only" pay attention to the image, or also to your code?

Please write down your problem mathematically. Then you basically have the answer in Matlab.

Answer 1

[Julian]

The size of your code and the size of the picture are different.

If you want the size of your code you have to change a and b in your matrices.

Calc = zeros(200,7200);

Table = zeros(200,7200);

for a = 2:size(Calc,1)

for b = 2:size(Calc,2)

Calc(a,b) = (Array1(b) * Array2(a,b)) + (Array1(b-1) * Array2(a-1,b-1));

end

Table(a,:) = Calc(a,:) / CONSTANT;

end

And you should try not to work with for-loops but with matrix operations. These are much faster in Matlab.

I don't know which dimensions are correct now, but for my code the quick variant should look like this:

Calc(2:end,2:end) = (Array1(2:end) .*Array2(2:end,2:end)) + (Array1(1:end-1) .*Array2(1:end-1,1:end-1));

Table = Calc/CONSTANT;

[malik abdelli]

yes but this still doesnt work they tell me that "Array indices must be positive integers or logical values."

I am assuming there is a problem with this " (Array1(b-1) * Array2(a-1,b-1))", since there is no value for Array1(0).

But i dont understand how i would do it otherwise

[Julian]

Oh, yes the loops have to start at 2 then, because otherwise you have 0 as index and in Matlab the indices start at 1.

[malik abdelli]

ok thank you