I am interesting to replace the diagonal of matrix D to 1,2,3,4. This is matrix D:
A=[1,2,3,4,2,3,4,5; 3,4,5,6,4,5,6,7]; D=[A;A]; D=[D D]; % size of matrix [4x16] % 
- 2what do u mean by the diagonal? D is a non-square matrix..Spectre– Spectre2013-03-28 09:05:46 +00:00Commented Mar 28, 2013 at 9:05
- @Kishore, a main diagonal is also defined for non-square matrices.George Aprilis– George Aprilis2013-03-28 09:15:08 +00:00Commented Mar 28, 2013 at 9:15
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1 Answer
To set the main diagonal to integers starting a 1 and incrementing by 1:
D(eye(4)==1) = 1:4 Or to generalize it:
n = min(size(D)); D(eye(n)==1) = 1:n; note here that the ==1 is to convert the output of eye(n), the identity matrix, to type logical.
EDIT:
This is just a guess at what you mean by all the diagonals but here goes:
n = size(D,1); m = size(D,2); I = repmat(eye(min([n,m])), ceil(n/m), ceil(m/n)); I = I(1:n, 1:m)==1 d = repmat(1:min([n,m]), 1, max([ceil(n/m), ceil(m/n)])); d = d(1:max(m,n)); D(I) = d 3 Comments
cenging
Hello dan, This change only 1 diagonal in matrix, I want to change all diagonals in matrix.
Dan
What other diagonals? Please provide a manually calculated example and add it to your question (edit your original question) so we can see what you mean.
Dan
No problem, please mark the answer as correct and upvote if you found it helpful (by clicking the arrow and the tick in the top left of this answer)