[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Octave-bug-tracker] [bug #55885] Wrong sparse LU permutation matrix wit

From: Rik
Subject: [Octave-bug-tracker] [bug #55885] Wrong sparse LU permutation matrix with vector option
Date: Mon, 11 Mar 2019 17:09:23 -0400 (EDT)
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko

Update of bug #55885 (project octave):

                  Status:                    None => Works For Me           


Follow-up Comment #1:

According to the documentation, when called with 4-outputs

[L, U, P, Q] = lu (S)

the resulting decomposition is

P*S*Q = L*U

When called with the "vector" argument, the resulting decomposition is

S(P,Q) = L*U

So to test, I should have

S(P,Q) - L*U = 0

octave:25> S = sprand (5,5,0.3);
octave:26> [L,U,P,Q] = lu (S, 'vector');
octave:27> S(P,Q) - L*U
ans =

Compressed Column Sparse (rows = 5, cols = 5, nnz = 0 [0%])

So this looks correct to me.

For the second point, it makes no difference for indexing whether the vectors
are row or column vectors.


Reply to this item at:


  Message sent via Savannah

reply via email to

[Prev in Thread] Current Thread [Next in Thread]