I've got the following error when applying bicg+sor to my problem: mt-soft/solveTest> ./solveTest -ksp_view -ksp_converged_reason -ksp_monitor_true_residual -log_summary -mat_type aij -ksp_rtol 1.0e-7 -ksp_type bicg -pc_type sor -ksp_max_it 750 [0]PETSC ERROR: --------------------- Error Message ------------------------------------ [0]PETSC ERROR: No support for this operation for this object type! [0]PETSC ERROR: PC does not have apply transpose! [0]PETSC ERROR: ------------------------------------------------------------------------ [0]PETSC ERROR: Petsc Development HG revision: 59ca71b85d784abbe22f12c34ffcb2ccc6dc68b0 HG Date: Tue Mar 20 01:05:13 2012 -0500 [0]PETSC ERROR: See docs/changes/index.html for recent updates. [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting. [0]PETSC ERROR: See docs/index.html for manual pages. [0]PETSC ERROR: ------------------------------------------------------------------------ [0]PETSC ERROR: Configure options --with-petsc-arch=openmpi-intel-complex-release-c --with-mpi-dir=/opt/mpi/intel/openmpi-1.4.2 --with-scalar-type=complex --with-precision=double --with-blas-lapack-dir=/usr/local/lib --with-x=0 --with-debugging=0 [0]PETSC ERROR: ------------------------------------------------------------------------ [0]PETSC ERROR: PCApplyTranspose() line 515 in /home/mt/agrayver/lib/petsc-dev/src/ksp/pc/interface/precon.c [0]PETSC ERROR: KSPSolve_BiCG() line 55 in /home/mt/agrayver/lib/petsc-dev/src/ksp/ksp/impls/bicg/bicg.c [0]PETSC ERROR: KSPSolve() line 434 in /home/mt/agrayver/lib/petsc-dev/src/ksp/ksp/interface/itfunc.c [0]PETSC ERROR: main() line 114 in /home/solveTest.c Any ideas? -- Regards, Alexander