Hi PETSc team: I am trying to solve a Stokes problem in a segregated manner, in which the pressure field is obtained by solving the pressure Schur complement. This is what I did.
I created a Schur complement by calling Mat S; MatCreateSchurComplement(gloAssem_ptr->K_11, gloAssem_ptr->K_11, gloAssem_ptr->K_10, gloAssem_ptr->K_01, gloAssem_ptr->K_00, &S); Then I use the Mat S as an input for KSP: KSPSetOperators(ksp, S, S); I got error message as follows. [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html for possible LU and Cholesky solvers [0]PETSC ERROR: Could not locate a solver package. Perhaps you must ./configure with --download-<package> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting. [0]PETSC ERROR: Petsc Release Version 3.8.3, Dec, 09, 2017 [0]PETSC ERROR: ./bipn3d on a arch-linux2-cxx-debug named bacon by luis Tue Jan 23 11:02:34 2018 [0]PETSC ERROR: Configure options --prefix=~/lib/petsc-3.8.3-debug --with-x=0 -with-pic --with-mpi-compilers=1 --with-mpi-dir=/home/lib/mpich-3.2/ --with-clanguage=C++ --with-scalar-type=real --with-shared-libraries=1 --with-precision=double --with-hypre=1 --download-hypre --with-spai=1 --download-spai --with-superlu_dist=1 --download-superlu_dist --with-superlu=1 --download-superlu --with-parmetis=1 --download-parmetis --with-metis=1 --download-metis --with-mumps=1 --download-mumps --with-parmetis=1 --download-parmetis --with-metis=1 --download-metis --with-scalapack=1 --download-scalapack --with-blacs=1 --download-blacs --with-spooles=1 --download-spooles --with-debugging=yes --download-fblaslapack [0]PETSC ERROR: #1 MatGetFactor() line 4346 in /home/lib/petsc-3.8.3/src/mat/interface/matrix.c [0]PETSC ERROR: #2 PCSetUp_ILU() line 142 in /home/lib/petsc-3.8.3/src/ksp/pc/impls/factor/ilu/ilu.c [0]PETSC ERROR: #3 PCSetUp() line 924 in /home/lib/petsc-3.8.3/src/ksp/pc/interface/precon.c [0]PETSC ERROR: #4 KSPSetUp() line 381 in /home/lib/petsc-3.8.3/src/ksp/ksp/interface/itfunc.c [0]PETSC ERROR: #5 KSPSolve() line 612 in /home/lib/petsc-3.8.3/src/ksp/ksp/interface/itfunc.c Let me know if you can see any issue in the usage of Schur complement creation. Thanks, Luis
