[Getfem-users] gesvd_interface

[Philipp Lamby]

Hello, 

I have got a question concerning lines 379 and 399 in 
gmm/gmm_lapack_interface.h:
    
   resize(U, m, n);     /* Why not resize(U, m, m); ? */ 

I think, in the SVD  X = U*S*V^T, the orthogonal Matrix U should have 
dimensions mxm.
After reading the LAPACK documentation, I do not see a reason why U should have 
n 
columns. Actually I think, if X is overdetermined (m>n) the current code might 
cause 
memory violations when calling the interfaced LAPACK routine. In my application 
X 
is underdetermined, and I stumbled later in my code, because I unexpectedly 
could 
not  multiply U^T with a vector of length m.  

Best regards, 
  Philipp Lamby