[petsc-users] Slepc Question, shell-matrix

[feng wang]

Hello,

I am new to Slepc and trying to work out the eigenvalues and eigenvectors of my Jacobian matrix. I am using a shell matrix to work out the matrix-vector product and I am using the default Krylov-schur method.

My first attempt was not successful and I got the following errors:

[0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[0]PETSC ERROR: Missing or incorrect user input
[0]PETSC ERROR: The inner product is not well defined: indefinite matrix
[0]PETSC ERROR: See https://petsc.org/release/faq/ for trouble shooting.
[0]PETSC ERROR: Petsc Release Version 3.17.4, unknown
[0]PETSC ERROR: cfdtest on a arch-debug named ming by feng Mon Aug 22 19:21:41 2022
[0]PETSC ERROR: Configure options --with-cc=mpicc --with-cxx=mpicxx --with-fc=0 PETSC_ARCH=arch-debug
[0]PETSC ERROR: #1 BV_SafeSqrt() at /home/feng/cfd/slepc-3.17.1/include/slepc/private/bvimpl.h:130
[0]PETSC ERROR: #2 BV_SquareRoot_Default() at /home/feng/cfd/slepc-3.17.1/include/slepc/private/bvimpl.h:365
[0]PETSC ERROR: #3 BVOrthogonalizeCGS1() at /home/feng/cfd/slepc-3.17.1/src/sys/classes/bv/interface/bvorthog.c:101
[0]PETSC ERROR: #4 BVOrthogonalizeGS() at /home/feng/cfd/slepc-3.17.1/src/sys/classes/bv/interface/bvorthog.c:177
[0]PETSC ERROR: #5 BVOrthonormalizeColumn() at /home/feng/cfd/slepc-3.17.1/src/sys/classes/bv/interface/bvorthog.c:402
[0]PETSC ERROR: #6 BVMatArnoldi() at /home/feng/cfd/slepc-3.17.1/src/sys/classes/bv/interface/bvkrylov.c:91
[0]PETSC ERROR: #7 EPSSolve_KrylovSchur_Default() at /home/feng/cfd/slepc-3.17.1/src/eps/impls/krylov/krylovschur/krylovschur.c:261
[0]PETSC ERROR: #8 EPSSolve() at /home/feng/cfd/slepc-3.17.1/src/eps/interface/epssolve.c:147
[0]PETSC ERROR: #9 slepc_eigen_comp() at domain/cfd/slepc_eigen_solve.cpp:77

Could someone please shine some light on this? I have also attached my code. The code is part of my big library and I cannot attach the whole code, sorry about this. but I am happy to provide more information. The attached code has some arrangements for halo exchange, but for the moment, it assumes it is a serial run.

Many thanks,
Feng
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