# How can I store the values of a diagonal using only a for loop?

25 views (last 30 days)
Jonas Morgner on 4 May 2022
Edited: Walter Roberson on 4 May 2022
%A
rng('default')
r2 = randi(100,3,3); % Creating a 3x3 matrix, with random values from 1 to 100
%B
d = diag(r2) % Obtain the diagonal elements
%C
Metod1 = d(2,1) % Using two parameters (row 2, column 1)
Metod2 = d(3) % Using one parametr (3rd element)
How can I create a new vector which only stores the diagonal using a for loop from the initial matrix?

Walter Roberson on 4 May 2022
If you loop from 1 to the minimum of the number of rows or columns, then for iteration K the element is at d(K,K)
If you want to use linear indexing, then note that once you know where one element of the diagonal is, that the next one is (rows + 1) elements further along. For example, 3 x 3, rows+1 is 4, and the diagonals are at (1), (1+4), (1+4+4)
##### 2 CommentsShowHide 1 older comment
Walter Roberson on 4 May 2022
Edited: Walter Roberson on 4 May 2022
for K = 1 : size(d,1)
d(K,K)
end
after that it becomes a matter of how to store the K'th value into the K'th element of a vector. If that is not something you are familiar with you should be considering running through MATLAB Onramp.