You are trying the default preconditioner ILU(0) which requires a square
matrix. Run with -pc_type none or see the manual page
KSPLSQR - This implements LSQR
Options Database Keys:
+ -ksp_lsqr_set_standard_error - Set Standard Error Estimates of Solution
see KSPLSQRSetStandardErrorVec()
. -ksp_lsqr_monitor - Monitor residual norm and norm of residual of normal
equations
- see KSPSolve()
Level: beginner
Notes:
This varient, when applied with no preconditioning is identical to the
original algorithm in exact arithematic; however, in practice, with no
preconditioning
due to inexact arithematic, it can converge differently. Hence when no
preconditioner is used (PCType PCNONE) it automatically reverts to the original
algorithm.
With the PETSc built-in preconditioners, such as ICC, one should call
KSPSetOperators(ksp,A,A'*A,...) since the preconditioner needs to work
for the normal equations A'*A.
Supports only left preconditioning.
References:The original unpreconditioned algorithm can be found in Paige and
Saunders, ACM Transactions on Mathematical Software, Vol 8, pp 43-71, 1982.
In exact arithmetic the LSQR method (with no preconditioning) is identical
to the KSPCG algorithm applied to the normal equations.
The preconditioned varient was implemented by Bas van't Hof and is
essentially a left preconditioning for the Normal Equations. It appears the
implementation with preconditioner
track the true norm of the residual and uses that in the convergence test.
Developer Notes: How is this related to the KSPCGNE implementation? One
difference is that KSPCGNE applies
the preconditioner transpose times the preconditioner, so one does
not need to pass A'*A as the third argument to KSPSetOperators().
For least squares problems without a zero to A*x = b, there are additional
convergence tests for the residual of the normal equations, A'*(b - Ax), see
KSPLSQRDefaultConverged()
.seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types),
KSP, KSPLSQRDefaultConverged()
Barry
On May 23, 2012, at 4:58 PM, Ildar Rakhmanov wrote:
> Here is full message:
>
> Matrix A after construction
> row 0: (0, 1) (1, 0)
> row 1: (0, 0) (1, 1)
> row 2: (0, 1) (1, 1)
> u
> 1
> 1
> b
> 0
> 0
> 0
> b
> 1
> 1
> 2
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: Invalid argument!
> [0]PETSC ERROR: Must be square matrix, rows 3 columns 2!
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Release Version 3.1.0, Patch 8, Thu Mar 17 13:37:48 CDT
> 2011
> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> [0]PETSC ERROR: See docs/index.html for manual pages.
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: ./lsqr on a linux-gnu named ildar by ildar Wed May 23
> 17:13:44 2012
> [0]PETSC ERROR: Libraries linked from /home/ildar/pbsm/lib
> [0]PETSC ERROR: Configure run at Sat Mar 3 12:01:22 2012
> [0]PETSC ERROR: Configure options --prefix=/home/ildar/pbsm
> --download-hypre=1 --download-spooles=1 --download-plapack=1
> --download-spai=1 --download-blacs=1 --download-triangle=1
> --download-f-blas-lapack=1 --download-umfpack=1 --download-sowing=1
> --download-c2html=1 --download-superlu_dist=1 --download-parmetis=1
> --download-scalapack=1 --download-superlu=1 --download-mumps=1
> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> [0]PETSC ERROR: MatGetOrdering() line 223 in src/mat/order/sorder.c
> [0]PETSC ERROR: PCSetUp_ILU() line 194 in src/ksp/pc/impls/factor/ilu/ilu.c
> [0]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c
> [0]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: KSPSolve() line 353 in src/ksp/ksp/interface/itfunc.c
> [0]PETSC ERROR: main() line 109 in "unknowndirectory/"lsqr.c
> application called MPI_Abort(MPI_COMM_WORLD, 62) - process 0
>
>
>
>
> On Wed, May 23, 2012 at 5:29 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> You cut and threw away the most important part of the error message. Where
> is the stack trace? Are we to guess where the error message was triggered?
> Please send the entire error message.
>
> Barry
>
> On May 23, 2012, at 4:15 PM, Ildar Rakhmanov wrote:
>
> > Hi,
> > I seems I am missing something. I want to use KSPLSQR.
> > I set up lsqr.c (see attachment)
> > it uses 3x2 matrix.
> >
> > The results is
> >
> > ildar at ildar:~/lsqr> ./lsqr
> > Matrix A after construction
> > row 0: (0, 1) (1, 0)
> > row 1: (0, 0) (1, 1)
> > row 2: (0, 1) (1, 1)
> > u
> > 1
> > 1
> > b
> > 0
> > 0
> > 0
> > b
> > 1
> > 1
> > 2
> > [0]PETSC ERROR: --------------------- Error Message
> > ------------------------------------
> > [0]PETSC ERROR: Invalid argument!
> > [0]PETSC ERROR: Must be square matrix, rows 3 columns 2!
> > [0]PETSC ERROR:
> > ------------------------------------------------------------------------
> >
> >
> >
> > Could any one point out how to correctly use LSQR solver?
> >
> > <lsqr.c>
>
>
