How to recover a square matrix from its upper triangular cell part?
9 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Hi all,
I'd like to compute the upper triangular part only for a symmetric matrix in a block by block way. After some operations I got this:
K>> tempBlk{:}
ans =
[6x6 double] [6x5 double] [6x5 double] [6x5 double]
[] [5x5 double] [5x5 double] [5x5 double]
[] [] [5x5 double] [5x5 double]
[] [] [] [5x5 double]
The cell blocks in the diagonal line here are full, symmetric, and the non-diagonal cell blocks are full, non-symmetric. The entire symmetric matrix result should be 21 by 21, which has the length and width of 6+5+5+5. I'd like to fill the empty cells (these [ ]) with zeros, then use cell2mat to transform it back to scalar matrix, then use triu to take only the upper triangular part.
Any idea of how to do this? Thanks!
0 Kommentare
Akzeptierte Antwort
Matt J
am 27 Jul. 2017
Bearbeitet: Matt J
am 27 Jul. 2017
There's no reason to fill the [] cells with zeros. You can fill them with anything, since they will eventually be overwritten with zeros by triu. I would therefore do as follows:
idx=cellfun('isempty', yourCellArray);
C=cellfun(@transpose,yourCellArray.','uni',0);
yourCellArray(idx)=C(idx);
result = triu(cell2mat(yourCellArray))
5 Kommentare
Matt J
am 27 Jul. 2017
Probably, but it will amount to a 25% saving at best. It would be better if, instead of cell2mat, you just allocated the final matrix at the very beginning and wrote into the blocks.
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Operating on Diagonal Matrices finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!