Hi, I add the following lines in the example /petsc/src/snes/examples/tutorials/ex19. When I run this example using different numbers of processors, n always equals to 1. However, according to the manual, n is the number of subproblems in the domain decomposition. I feel confused why n does not return the number of processors, could you explain it? Thanks! PetscInt n; DM *subdms; ierr =DMCreateDomainDecomposition(da,&n,NULL,NULL,NULL,&subdms);CHKERRQ(ierr); PetscPrintf(PETSC_COMM_WORLD,"### n==%d\n", n); Output: ### n==1 -- ------------------------------ This message and its contents, including attachments are intended solely for the original recipient. If you are not the intended recipient or have received this message in error, please notify me immediately and delete this message from your computer system. Any unauthorized use or distribution is prohibited. Please consider the environment before printing this email.