[petsc-users] Nonconforming object sizes ERROR

[Brian Yang]

Wow, it works... LSQR is fine with the problem. Thanks!

On Wed, Nov 12, 2014 at 3:06 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Oh, right CG only works for square matrices.
>
>   I think you should be using lsqr. See
> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPLSQR.html
> Note if you want to use preconditioning you need to pass for the second
> matrix the product of the transpose of the matrix times the matrix.
>
>   There is also KSPCGNE but the docs say, I don't know why, that one
> should use lsqr for least squares problems.
>
>   Basically our current support for overdetermined systems is not great
> and we need help.
>
>   Barry
>
> > On Nov 12, 2014, at 2:46 PM, Brian Yang <brianyang1106 at gmail.com> wrote:
> >
> > Thank you for the prompt response. I checked and my usage of KSPSolve is
> correct.
> >
> > Besides, the assertion line is:
> > if (mat->rmap->N != y->map->N)
> SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Mat mat,Vec y: global dim %D
> %D",mat->rmap->N,y->map->N);
> >
> > On Wed, Nov 12, 2014 at 2:29 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >   The calling sequence for KSPSolve is KSPSolve(KSP ksp,Vec b,Vec x),
> perhaps you have the b and the x backwards in your call?
> >
> >   Barry
> >
> > > On Nov 12, 2014, at 2:23 PM, Brian Yang <brianyang1106 at gmail.com>
> wrote:
> > >
> > > Hi,
> > >
> > > I am solving an over-determined linear system Ax=b and b=0.
> > >
> > > A size: 296856 x 14430
> > > x (non-zero guess): 14430
> > > b (zero): 296856
> > >
> > > All of them are using seq mode to create, so one node will solve this.
> However I got this error:
> > >
> > > [0]PETSC ERROR: Nonconforming object sizes!
> > > [0]PETSC ERROR: Mat mat,Vec y: global dim 296856 14430!
> > >
> > > [0]PETSC ERROR:
> ------------------------------------------------------------------------
> > > [0]PETSC ERROR: MatMult() line 2171 in src/mat/interface/matrix.c
> > > [0]PETSC ERROR: KSP_MatMult() line 204 in
> src/ksp/ksp/impls/cg//datadb/raafat/src/petsc-3.4.3/include/petsc-private/kspimpl.h
> > > [0]PETSC ERROR: KSPSolve_CG() line 132 in src/ksp/ksp/impls/cg/cg.c
> > > [0]PETSC ERROR: KSPSolve() line 441 in src/ksp/ksp/interface/itfunc.c
> > >
> > >
> > > Any restrictions here or I misunderstood something? Thanks!
> > >
> > > --
> > > Brian Yang
> > > U of Houston
> > >
> > >
> > >
> >
> >
> >
> >
> > --
> > Brian Yang
> > U of Houston
> >
> >
> >
>
>


-- 
Brian Yang
U of Houston
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