help in adding a descending order a symetric matric
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ana take
el 16 de En. de 2017
Comentada: ana take
el 17 de En. de 2017
Hello! I want to put in a descending order just the part upper the main diagonal in a symmetric matrix and to get the index of those elements. What should I change in this code?
function [values,i,j] = max(A,n)
[a, linIdx] = sort(A(:),'descend');
values = a(1:n);
[i,j] = ind2sub(size(A),linIdx(1:n));
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Walter Roberson
el 17 de En. de 2017
Please do not call your function "max" as that interferes with using the key MATLAB routine "max"
Respuesta aceptada
John Chilleri
el 16 de En. de 2017
Editada: John Chilleri
el 16 de En. de 2017
Hello,
Here's a very inelegant solution, but it does the job. I'm making all values below the main diagonal -Inf so that they're guaranteed to not be apart of the a(1:n) when you sort, assuming your original matrix does not contain -Infinities (this also includes the main diagonal, I can change it to exclude it if necessary).
function [values,i,j] = whateveryouwanttocallit(A,n)
low = tril(A-Inf,-1)+1;
A = low.*A;
[a, linIdx] = sort(A(:),'descend');
values = a(1:n);
[i,j] = ind2sub(size(A),linIdx(1:n));
end
Hope this helps!
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Walter Roberson
el 17 de En. de 2017
See https://www.mathworks.com/matlabcentral/newsreader/view_thread/278808 for information on extracting the upper diagonal.
However, the question arises of which index you are looking for. Are you looking for an index relative to the vector of extracted values, or are you looking for the index into the original matrix?
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