Problem with a for loop?

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malik abdelli
malik abdelli 2023-9-7
编辑： Julian 2023-9-7
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
%%%%
I would be very grateful if someone could help .
Thanks in advance.
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malik abdelli
malik abdelli 2023-9-7
yes thank you i just corrected it
Julian
Julian 2023-9-7
编辑：Julian 2023-9-7
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.

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Julian
Julian 2023-9-7
编辑：Julian 2023-9-7
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;
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Julian
Julian 2023-9-7
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.

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