[petsc-users] Errors encountered with KSPsolver with MATNEST and VECNEST

[Barry Smith]

  From the error message the second vector you are using to form the nest vector has not been completely created/set up. Make sure you called either VecCreateSeq(), VecCreateMPI() or did VecCreate(), VecSetType(), VecSetUp() and if it is the right hand side make sure you put numerical values in it.

   Barry


> On Jul 15, 2020, at 1:05 PM, Karl Yang <y.juntao at hotmail.com> wrote:
> 
> Hello,
> 
> I'm trying to solve a 2*2 block matrix system.
> I managed to form a 2*2 MatNest and a 21 VecNest. However when I try to  make use of ksp solve, I encounter the following error. There is only one or two examples on MatNest and VecNest. I could not figure out what could be the trouble.
> 
> 
> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [0]PETSC ERROR: Invalid argument
> [0]PETSC ERROR: Nest vector argument 2 not setup.
> [0]PETSC ERROR: See https://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.12.5, Mar, 29, 2020
> [0]PETSC ERROR: ./testSolve on a arch-linux2-c-debug named f601294ac804 by Unknown Thu Jul 16 01:56:11 2020
> [0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++ --with-fc=gfortran --download-mpich --download-fblaslapack --with-cuda
> [0]PETSC ERROR: #1 VecCopy_Nest() line 68 in /usr/local/petsc/petsc-3.12.5/src/vec/vec/impls/nest/vecnest.c
> [0]PETSC ERROR: #2 VecCopy() line 1577 in /usr/local/petsc/petsc-3.12.5/src/vec/vec/interface/vector.c
> [0]PETSC ERROR: #3 KSPInitialResidual() line 61 in /usr/local/petsc/petsc-3.12.5/src/ksp/ksp/interface/itres.c
> [0]PETSC ERROR: #4 KSPSolve_GMRES() line 236 in /usr/local/petsc/petsc-3.12.5/src/ksp/ksp/impls/gmres/gmres.c
> [0]PETSC ERROR: #5 KSPSolve() line 760 in /usr/local/petsc/petsc-3.12.5/src/ksp/ksp/interface/itfunc.c
> 
> 
> Regards
> JT
> 

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