[petsc-users] Slepc SVDCyclicSetExplicitMatrix does not prealloc memory?

[Gong Ding]

Hi,
I am stiall dealing with the ill conditioned problem. :-(
Yesderday, I installed slepc-3.1-p6 for SVD calculation of my matrix.

The SVD solver works well for the largest singualr value calculation.
But for the smallest singualr value, all most all the methods fail.

Finally, I chosen the most inefficient way. 
That build the cyclic matrix explicitly with 
shift-and-invert spectral transformation.
And solve the eigen value problem by LU preconditioned GMRES.
The preconditioner should be superlu rather than others.
I guess the reason is superlu use static pivot. 
Because solver with partial pivot such as mumps can not work.
Anyway, slepc solved my problem. 

However, the explicit building cyclic matrix takes too long to finish.
The log info says 

[0] MatSetUpPreallocation(): Warning not preallocating matrix storage
[0] MatAssemblyEnd_SeqAIJ(): Matrix size: 35038 X 35038; storage space: 325302 unneeded,482948 used
[0] MatAssemblyEnd_SeqAIJ(): Number of mallocs during MatSetValues() is 42204
[0] MatAssemblyEnd_SeqAIJ(): Maximum nonzeros in any row is 33
[0] Mat_CheckInode(): Found 26800 nodes of 35038. Limit used: 5. Using Inode routines

It seems no preallocation for cyclic matrix. Is it a bug or I forgot something?