[petsc-users] Problem with Finding Eigenvalues using SLEPc

[Jose E. Roman]

Before using EPS, try something like this and see if you get the same error:

call MatGetVecs(A,v,w,ierr)
call MatMult(A,v,w,ierr)

Jose

El 27/09/2012, a las 14:55, Paul Cruise escribió:

> The error messages that I have is,
> 
> [0]PETSC ERROR: --------------------- Error Message ------------------------------------
> [0]PETSC ERROR: Floating point exception!
> [0]PETSC ERROR: Vec entry at local location 0 is not-a-number or infinite at beginning of function: Parameter number 2!
> [0]PETSC ERROR: ------------------------------------------------------------------------
> [0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 2, Fri Jul 13 15:42:00 CDT 2012
> [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: /gpfs/home/swayamjyoti_s/slepc-3.3/src/eps/examples/tutorials/Test/ex1f on a arch-linu named merlinc19 by swayamjyoti_s Thu Sep 27 14:20:49 2012
> [0]PETSC ERROR: Libraries linked from /gpfs/home/swayamjyoti_s/petsc-3.3/arch-linux2-c-debug/lib
> [0]PETSC ERROR: Configure run at Tue Aug 21 15:47:21 2012
> [0]PETSC ERROR: Configure options --with-fc=ifort --download-f-blas-lapack --download-mpich
> [0]PETSC ERROR: ------------------------------------------------------------------------
> [0]PETSC ERROR: MatMult() line 2081 in /gpfs/home/swayamjyoti_s/petsc-3.3/src/mat/interface/matrix.c
> [0]PETSC ERROR: STApply_Shift() line 41 in src/st/impls/shift/shift.c
> [0]PETSC ERROR: STApply() line 67 in src/st/interface/stsolve.c
> [0]PETSC ERROR: EPSFullLanczos() line 179 in src/eps/impls/krylov/krylov.c
> [0]PETSC ERROR: EPSSolve_KrylovSchur_Symm() line 58 in src/eps/impls/krylov/krylovschur/ks-symm.c
> [0]PETSC ERROR: EPSSolve() line 130 in src/eps/interface/solve.c
> 
> Could someone please help how to fix these?
> 
> 
> On Thu, Sep 27, 2012 at 2:12 PM, Paul Cruise <paul.cruise.paul at gmail.com> wrote:
> 
> Hello,
> 
> I input a hessian matrix of size (5148 X 5148 size) into SLEPc to find it's eigenvalues (using EPS) as follows:
> 
> call MatCreate(PETSC_COMM_WORLD,A,ierr)
>       call MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,3*natoms,3*natoms,ierr)
>       call MatSetFromOptions(A,ierr)
>       call MatSetUp(A,ierr)
> 
>       do n=1,number_of_elements
>               call MatSetValues(A,3*natoms,indices(n,1),3*natoms,indices(n,2),elements(n),INSERT_VALUES,ierr)
>       end do
> 
>       call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr)
>       call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr)
> 
> But somehow, the eigenvalues do not seem to converge as I find the following output:
> 
>  Number of iterations of the method:   1
>  Solution method: krylovschur
>  Number of requested eigenvalues: 1
>  Number of iterations of the method:   1
>  Solution method: krylovschur
>  Number of requested eigenvalues: 1
>  Stopping condition: tol=1.0000E-08, maxit= 648
>  Number of converged eigenpairs: 0
> 
> Can someone please tell me what's the problem, because this matrix for sure has eigenvalues as I have obtained before without using SLEPc?
> 
> Thanks & Regards,
> Paul
> 
> 
> 
> 
>