[petsc-users] About Preconditioner and MUMPS

Hello, I have some questions about pc and mumps_icntl. 1. What’s the difference between adopt preconditioner by code (for example, PetscCall(PCSetType(pc,PCLU)) and option -pc_type lu?? And also, What’s the priority between code pcsettype and option -pc_type ?? 2. When I tried to use METIS in MUMPS, I adopted metis by option (for example, -mat_mumps_icntl_7 5). In this situation, it is impossible to use metis without pc_type lu. However, in my case pc type lu makes the performance poor. So I don’t want to use lu preconditioner. How can I do this? Thanks, Hyung Kim