On Feb 21, 2011, at 3:37 PM, Jed Brown wrote:

ierr = DMDAGetInfo(dac,&dimc,&Mc,&Nc,&Pc,&mc,&nc,&pc,&dofc,&sc,&wrapc,&stc);CHKERRQ(ierr); ierr = DMDAGetInfo(daf,&dimf,&Mf,&Nf,&Pf,&mf,&nf,&pf,&doff,&sf,&wrapf,&stf);CHKERRQ(ierr); if (dimc != dimf) SETERRQ2(((PetscObject)daf)->comm,PETSC_ERR_ARG_INCOMP,"Dimensions of DMDA do not match %D %D",dimc,dimf);CHKERRQ(ierr); if (dofc != doff) SETERRQ2(((PetscObject)daf)->comm,PETSC_ERR_ARG_INCOMP,"DOF of DMDA do not match %D %D",dofc,doff);CHKERRQ(ierr); if (sc != sf) SETERRQ2(((PetscObject)daf)->comm,PETSC_ERR_ARG_INCOMP,"Stencil width of DMDA do not match %D %D",sc,sf);CHKERRQ(ierr); if (wrapc != wrapf) SETERRQ(((PetscObject)daf)->comm,PETSC_ERR_ARG_INCOMP,"Periodic type different in two DMDAs");CHKERRQ(ierr); if (stc != stf) SETERRQ(((PetscObject)daf)->comm,PETSC_ERR_ARG_INCOMP,"Stencil type different in two DMDAs");CHKERRQ(ierr); if (Mc < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Coarse grid requires at least 2 points in x direction"); if (dimc > 1 && Nc < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Coarse grid requires at least 2 points in y direction"); if (dimc > 2 && Pc < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Coarse grid requires at least 2 points in z direction");

Several of these are not necessary. DMGetInjection_DA_3D:

ierr = DMDAGetInfo(dac,0,&Mx,&My,&Mz,0,0,0,0,0,&pt,0);CHKERRQ(ierr); ierr = DMDAGetInfo(daf,0,&mx,&my,&mz,0,0,0,&dof,0,0,0);CHKERRQ(ierr);

Seems silly to fail when not necessary. I'm inclined to move the guards into the specific implementation so that only the necessary amount of consistency needs to be checked. How about getting rid of DMGetInjection_DA entirely and just set the appropriate ops slot?

Right. Feel free to split it apart into the separate functions that go into the slot and remove the DMGetInjection_DA It is just of this style because it was coded before DM was a gleam in my eye and needs refactoring Barry