How do I make a lower triangular matrix from a column vector?
46 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
I am trying to make a lower triangular matrix from a column vector to then produce a fully populated 24x24 symmetric matrix.
The column vector I'm using (A as a simple example) has 300 elements and I need to populate the triangular matrix (B as a simple example) as follows:
A = [i1 i2 i3 i4 i5 i6 i7 i8 i9 i10 ...]
B = [i1; i2 i3; i4 i5 i6; i7 i8 i9 i10; ....]
Any help would be appreciated. It may be that it's easier to make the symmetric matrix straight away, if so I'm open to suggestions. Thanks in advance.
0 commentaires
Réponse acceptée
Plus de réponses (1)
Rik
le 9 Mar 2021
The functions you should be looking for are tril and triu. You should be using triu, because you seem to want to fill your array in row-major order, while the Matlab default is column-major.
A=1:21;%replace with your data
%sz will only be a positive integer if numel(A) is a triangle number
sz=-0.5+sqrt(0.25-4*0.5*-numel(A));
B=triu(ones(sz));
B(logical(B))=A;
B=B.';
disp(B)
2 commentaires
Rik
le 29 Mar 2021
Similar to Jan, my Python skill are only rudimentary. If you are an actual Python user, your success in googling documentation will probably be higher.
Voir également
Catégories
En savoir plus sur Call Python from MATLAB dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!