[petsc-users] Could DMComposite handle two vectors with different grid sizes.

[(Rebecca) Xuefei YUAN]

Dear all,

If I have two different vectors (with different dof, stencil width and  
grid sizes), could I use DMComposite to handle this?

The following is the piece of code for assemble this DMComposite in DMMG.

	tempparameters.mxfield				= 5;
	tempparameters.myfield				= 5;

	tempparameters.mxgrid	= tempparameters.mxfield+1;
	tempparameters.mygrid	= tempparameters.myfield+1;

	ierr	= DMMGCreate(comm, tempparameters.numberOfLevels, &appCtx,  
&dmmg);CHKERRQ(ierr);

	ierr	= DMCompositeCreate(comm,&packer);CHKERRQ(ierr);

	ierr	= DACreate2d(comm,DA_NONPERIODIC,DA_STENCIL_BOX,  
tempparameters.mxfield, tempparameters.myfield, PETSC_DECIDE,  
PETSC_DECIDE, 4, 3, PETSC_NULL, PETSC_NULL, &da_fff);CHKERRQ(ierr);
	ierr	= DASetFieldName(da_fff, 0, "phi");CHKERRQ(ierr);
	ierr	= DASetFieldName(da_fff, 1, "vz");CHKERRQ(ierr);
	ierr	= DASetFieldName(da_fff, 2, "psi");CHKERRQ(ierr);
	ierr	= DASetFieldName(da_fff, 3, "bz");CHKERRQ(ierr);
	ierr	= DACreate2d(comm,DA_NONPERIODIC,DA_STENCIL_BOX,  
tempparameters.mxgrid, tempparameters.mygrid, PETSC_DECIDE,  
PETSC_DECIDE, 1, tempparameters.gridStencilWidth, PETSC_NULL,  
PETSC_NULL, &da_ggg);CHKERRQ(ierr);
	ierr	= DASetFieldName(da_ggg, 0, "disp");CHKERRQ(ierr);

	ierr	= DMCompositeAddDM(packer,(DM)da_fff);CHKERRQ(ierr);
	ierr	= DMCompositeAddDM(packer,(DM)da_ggg);CHKERRQ(ierr);
	ierr	= DMCompositeAddArray(packer,0,1);CHKERRQ(ierr);

	ierr	= DMMGSetDM(dmmg, (DM)packer);CHKERRQ(ierr);

	ierr	= DADestroy(da_fff);CHKERRQ(ierr);
	ierr	= DADestroy(da_ggg);CHKERRQ(ierr);

.........................................................

	ierr	= DMCompositeDestroy(packer);CHKERRQ(ierr);
	ierr	= DMMGDestroy(dmmg);CHKERRQ(ierr);


I understand that for numberOfLevels(nl)>1, the grid size difference  
is no longer 1, but 3(nl=2), 5(nl=3), could I use DMComposite to  
handle such a case successfully?

I was not able to get examples for such a case, is there any?

Thanks a lot!



-- 
(Rebecca) Xuefei YUAN
Department of Applied Physics and Applied Mathematics
Columbia University
Tel:917-399-8032
www.columbia.edu/~xy2102