How to find maximum square zero matrix through the biggest matrix?
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Serafettin Bal
le 17 Juin 2021
Commenté : Atsushi Ueno
le 22 Juin 2021
how to plot a picture in matlab?
Below is the code that generates a random 6*6 diagonal square matrix.
And, the resulting random matrix (Mout) is here.
For example, the largest square zero matrix for this matrix is as follows.
4*4 Square zero matrix for the 6*6 square matrix.
So, how can I find the size of the maximum square zero matrix that can be created from this matrix?
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Rik
le 22 Juin 2021
Modifié(e) : Rik
le 22 Juin 2021
I recovered the removed content from the Google cache (something which anyone can do). Editing away your question is very rude. Someone spent time reading your question, understanding your issue, figuring out the solution, and writing an answer. Now you repay that kindness by ensuring that the next person with a similar question can't benefit from this answer.
The image of the code was later replaced by this:
N = randi([6 6],1);
M = randi([0 1], N);
Mu = triu(M);
Ml = Mu';
Mout = Mu + Ml;
Mout = Mout - diag(diag(Mout));
G = graph(Mout,'lower');
plot(G)
Atsushi Ueno
le 22 Juin 2021
@Rik Thank you for your recovering action. I can read back the comment left by the questioner in the history, so I will answer it.
Réponse acceptée
Atsushi Ueno
le 18 Juin 2021
What I did is:
- Solving Find the biggest empty box - MATLAB Cody - MATLAB Central (mathworks.com)
- Cheating other solution! --> "Finding 2D convolution with ones = 0" is the best idea
- To find the square that can wrap across the edges: repmat(Mout,2) does work for the issue
If there are square zero matrices of the same size, the upper left one will be selected.
Sorry, it is not tested well.
N = randi([6 6],1);
M = randi([0 1], N);
Mu = triu(M);
Ml = Mu';
Mout = Mu + Ml;
Mout = Mout - diag(diag(Mout));
G = graph(Mout,'lower');
plot(G);
Mout4 = repmat(Mout,2);
for k = 1:length(Mout)
[r,c] = find(~conv2(Mout4,ones(k),'valid'),1);
if r
k % k is the size of the square zero matrix
r % r is the row index of the square zero matrix
c % c is the column index of the square zero matrix
end
end
2 commentaires
Atsushi Ueno
le 19 Juin 2021
I'm sorry. I got a lot of questions to answer, but I slept for 12 hours afterwards.
Atsushi Ueno
le 22 Juin 2021
>every runs (because Mout matris created randomly) return the same output. k=1 r=1 c=1 k=2 r=1 c=1
@Serafettin Bal Yes, most of the patters created randomly have small squares. Why don't you create some matrix has bigger chank of zero for testing? The logic I wrote finds the square of zero from smaller one to bigger one. And the last printed out 'k' is the size of the maximum square zero matrix.
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