[petsc-users] Slepc: Computing first 4 smallest eigenvalues and eigenvectors of a large graph Laplacian

[Jose E. Roman]

> El 26 mar 2017, a las 6:08, Bodhisatta Pramanik <bodhi91 at iastate.edu> escribió:
> 
> Send all the output in the error message:
> 
> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [0]PETSC ERROR: Object is in wrong state
> [0]PETSC ERROR: Must call EPSSolve() first: Parameter #1
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.7.5, Jan, 01, 2017 
> [0]PETSC ERROR: ./RunPart on a arch-linux2-c-debug named research-5.ece.iastate.edu by bodhi91 Sat Mar 25 22:33:56 2017
> [0]PETSC ERROR: Configure options --with-cc=gcc --with-css=g++ -with-fc=gfortran --download-fblaslapack --download-mpich
> [0]PETSC ERROR: #10468 EPSComputeError() line 643 in /tmp/Bodhi/slepc-3.7.3/src/eps/interface/epssolve.c
>          0.000000     2.0795e-317
> 

The error is in EPSComputeError(), not in EPSSolve(). Did you modify the state of the EPS object between EPSSolve() and EPSComputeError()?

In graph partitioning, I would strongly recommend deflating the eigenvector corresponding to the zero eigenvalue, as is done in ex11.c:
http://slepc.upv.es/documentation/current/src/eps/examples/tutorials/ex11.c.html

Jose