[petsc-users] EPSGetEigenpair Error

[Eda Oktay]

Hello,

I am using EPSGetEigenpair to find some matrices' eigenpairs:

ierr = EPSGetType(eps,&type);CHKERRQ(ierr)
  ierr = EPSGetDimensions(eps,&nev,NULL,NULL);CHKERRQ(ierr);
  ierr = MatCreateVecs(L,&vr,NULL);CHKERRQ(ierr);
  Vec *V;
  VecDuplicateVecs(vr,nev,&V);
  for (i=0; i<nev;i++){
  ierr = EPSGetEigenpair(eps,i,&kr,NULL,V[i],NULL);
  }

However, for some matrices, even though nev = 2, I am getting the
following error:

[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------
[0]PETSC ERROR: Argument out of range
[0]PETSC ERROR: Argument 2 out of range
[0]PETSC ERROR: See
https://www.mcs.anl.gov/petsc/documentation/faq.html for trouble
shooting.
[0]PETSC ERROR: Petsc Release Version 3.13.2, Jun 02, 2020
[0]PETSC ERROR: ./deneme_new_vecscatter_arastep on a
arch-linux2-c-debug named b342.wls.metu.edu.tr by edaoktay Mon Jul  6
12:01:14 2020
[0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++
--download-mpich --download-openblas --download-slepc --download-metis
--download-parmetis --download-chaco --with-X=1
[0]PETSC ERROR: #1 EPSGetEigenpair() line 411 in
/home/edaoktay/petsc-3.13.2/arch-linux2-c-debug/externalpackages/git.slepc/src/eps/interface/epssolve.c

===================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   PID 8635 RUNNING AT b342.wls.metu.edu.tr
=   EXIT CODE: 134
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================
YOUR APPLICATION TERMINATED WITH THE EXIT STRING: Aborted (signal 6)
This typically refers to a problem with your application.
Please see the FAQ page for debugging suggestions

What can be the reason? I am getting this message when i = 0, so how
can 0 be out of range for nev = 2?

And why am I getting this message for 2 matrices out of 16?

Thanks!