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

[Bodhisatta Pramanik]

*First set a new PETSC_ARCH say arch-opt and ./configure with the
additional argument --with-debugging=0 then recompile PETSc with the new
PETSC_ARCH and recompile your code then send the new -log_view output.*
   I have attached the new log summary with this file. The computation time
is a lot faster now. It takes around 23 seconds to compute the first 3
eigenvectors of a 200K sized matrix.

Thanks,
Bodhi

On Sun, Mar 26, 2017 at 3:14 AM, Bodhisatta Pramanik <bodhi91 at iastate.edu>
wrote:

> *The error is in EPSComputeError(), not in EPSSolve(). Did you modify the
> state of the EPS object between EPSSolve() and EPSComputeError()?*
>
> I am not modifying the eps object. I have copied a part of the code where
> I am computing the eigenvectors.
>
>         EPSCreate(PETSC_COMM_WORLD,&eps);
>         EPSSetOperators(eps,m.Lpl,NULL);
>         EPSSetProblemType(eps,EPS_HEP);
>         EPSSetFromOptions(eps);
>
>         EPSSolve(eps);  //Solving for the eigenvalues
>
>         EPSGetIterationNumber(eps,&its);
>         PetscPrintf(PETSC_COMM_WORLD,"Number of iterations of the method:
> %D\n",its);
>         EPSGetType(eps,&type);
>         PetscPrintf(PETSC_COMM_WORLD,"Solution Method: %s\n\n",type);
>         EPSGetTolerances(eps,&get_tol,&maxit);
>         PetscPrintf(PETSC_COMM_WORLD,"Stopping condition: tol=%.4g,
> maxit=%D\n",(double)get_tol,maxit);
>         EPSGetConverged(eps,&nconv);
>         PetscPrintf(PETSC_COMM_WORLD, "Number of converged eigenpairs:
> %D\n\n",nconv);
>         if(nconv>0)
>         {
>                 PetscPrintf(PETSC_COMM_WORLD,
>                         "       k       ||Ax-kx||/||kx||\n"
>                         "-------------- ----------------\n");
>                 for(i=0;i<nconv;i++)
>                 {
>                         EPSGetEigenpair(eps,i,&kr,&ki,xr,xi);
>                         EPSComputeError(eps,i,EPS_ERROR_RELATIVE,&error);
>                         re = PetscRealPart(kr);
>                         im = PetscImaginaryPart(kr);
>
>                         re = kr;
>                         im = ki;
>                         if(im!=0.0) {
>                                 PetscPrintf(PETSC_COMM_WORLD," %9f%+9fi
> %12g\n",(double)re,(double)im,(double)error);
>                         }
>                         else {
>                                 PetscPrintf(PETSC_COMM_WORLD,"     %12f
>  %12g\n",(double)re,(double)error);
>                         }
>                 }
>                 PetscPrintf(PETSC_COMM_WORLD,"\n");
>         }
>
>         EPSDestroy(&eps);
>         VecDestroy(&xr);
>         VecDestroy(&xi);
> }
>
> This is what I pass through my command line:
> ./RunPart -eps_type jd -eps_nev 3 -st_ksp_type cg -st_ksp_rtol 0.001
> -eps_tol 0.001 -st_pc_type bjacobi -eps_smallest_real
>
>
> *In graph partitioning, I would strongly recommend deflating the
> eigenvector corresponding to the zero eigenvalue, as is done in ex11.c:*
>         I have tried doing this but for some reason the eigenvalues fail
> to converge.
>
>
>
> On Sun, Mar 26, 2017 at 2:41 AM, Jose E. Roman <jroman at dsic.upv.es> wrote:
>
>>
>> > 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
>>
>>
>
>
> --
> *Bodhisatta Pramanik,*
> *Graduate Student,*
> *Department of Electrical and Computer Engineering,*
> *301 Durham,*
> *Iowa State University,*
> *Ames,Iowa 50011,*
> bodhi91 at iastate.edu
> *515-735-6300 <(515)%20735-6300>*
>



-- 
*Bodhisatta Pramanik,*
*Graduate Student,*
*Department of Electrical and Computer Engineering,*
*301 Durham,*
*Iowa State University,*
*Ames,Iowa 50011,*
bodhi91 at iastate.edu
*515-735-6300*
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