[petsc-users] Problem with Finding Eigenvalues using SLEPc

[Paul Cruise]

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
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