for loop collecting output

F is giving me the same measurements and I can’t seem to find how to move to the next position.

A = (:,:,1)  % There are 100 A symmetric matrix
for i = 1:100A
F(i)    = atan(-(A(3,1)/A(3,2))) % Second A should be position (A(3,4).....
end

Answer 1

[Stephan]

Hi,

it is not recommended to use i - since i is reserved for complex numbers. Perhaps use k or n or ii instead. I decided to use ii:

The idea is to work with the counter variable ii in this context. That means you have to find a way to express the steps of the loop by your counter variable. For example:

for ii = 1:99
    F(ii)    = atan(-(A(3,ii)/A(3,ii+1)))
end

would make the pairs:

ii = 1  --> A(3,1) / A(3,2)
ii = 2  --> A(3,2) / A(3,3)
ii = 3  --> A(3,3) / A(3,4)
...
ii = 99 --> A(3,99 / A(3,100)

I leave it to you to find an expression that counts the way you need it.

Best regards

Stephan

[Nikolaos Zafirakis]

Hello Stephan,

To be honest with you I know how the indexing already works. My problem is more in the counter because I have 100 matrix and i need my loop to take one matrix in at a time do you have any advice for this? Thanks for your reply!

kind regards,

Nik

[madhan ravi]

Preallocation is essential.

[Stephan]

This takes first and second Matrix from A, then second and third and writes the results in the preallocated F Array:

A = randi(10,3,3,3)
F = nan(3,3,2)

for ii = 1:size(A,3)-1
    F(:,:,ii) = atan(-(A(:,:,ii)/A(:,:,ii+1)))
end

[Nikolaos Zafirakis]

I have a loop and I want to collect the output? the answer you give me does not satisfy the output as I need to keep all the A the way they are any suggestions?

A are arrays 0:300

for i = 0:3:300

Fi = atan(-(A5(1,1+i)/A5(1,2+i)));

Theta = acos(A5(1,3+i));

Psi = atan(A3(1,3+1)/A4(1,3+i));

end

[Steven Lord]

I'm not certain I understand what you're trying to compute. Can you show us exactly what the results should be for the following A vector?

A = 1:9;

[Stephan]

I agree - we would need a example to be sure understanding you correctly