DMShell and Other DM Types

This page documents DMShell (user-defined DM), DMProduct (Cartesian product of DMs), DMRedundant (redundantly-stored DM), and DMComposite (deprecated composite DM).

DMShell

DMShell allows users to define custom DM implementations by providing callback functions for operations like creating vectors, matrices, and managing topology.

Basic DMShell Usage

using PETSc, MPI

# Initialize MPI and PETSc
MPI.Init()
petsclib = PETSc.getlib()
PETSc.initialize(petsclib)

# Create a DMShell (returns a PetscDM) and set callbacks
shell = LibPETSc.DMShellCreate(petsclib, MPI.COMM_WORLD)
# Set callbacks on the returned DM, for example:
# LibPETSc.DMShellSetCreateGlobalVector(petsclib, shell, ...)
# LibPETSc.DMShellSetCreateLocalVector(petsclib, shell, ...)
# LibPETSc.DMShellSetCreateMatrix(petsclib, shell, ...)

# Set up
LibPETSc.DMSetUp(petsclib, shell)

# Cleanup
LibPETSc.DMDestroy(petsclib, shell)

# Finalize PETSc and MPI
PETSc.finalize(petsclib)
MPI.Finalize()

DMProduct

DMProduct represents a Cartesian product of multiple DMs, useful for coupled multi-physics problems.

Basic DMProduct Usage

using PETSc, MPI

# Initialize MPI and PETSc
MPI.Init()
petsclib = PETSc.getlib()
PETSc.initialize(petsclib)

# Create component DMs
dm1 = Ref{LibPETSc.CDM}()
dm2 = Ref{LibPETSc.CDM}()
# ... create dm1 and dm2 ...

# Create DMProduct
# Create two simple component DMs (here using small box DMPlex meshes)
dm1 = LibPETSc.DMPlexCreateBoxMesh(
    petsclib, MPI.COMM_WORLD, 2, LibPETSc.PETSC_FALSE,
    [1,1], [0.0,0.0], [1.0,1.0], [LibPETSc.DM_BOUNDARY_NONE, LibPETSc.DM_BOUNDARY_NONE], LibPETSc.PETSC_TRUE, 0, LibPETSc.PETSC_FALSE
)
dm2 = LibPETSc.DMPlexCreateBoxMesh(
    petsclib, MPI.COMM_WORLD, 2, LibPETSc.PETSC_FALSE,
    [1,1], [0.0,0.0], [1.0,1.0], [LibPETSc.DM_BOUNDARY_NONE, LibPETSc.DM_BOUNDARY_NONE], LibPETSc.PETSC_TRUE, 0, LibPETSc.PETSC_FALSE
)

# Create a DMProduct and attach component DMs
product = LibPETSc.DMCreate(petsclib, MPI.COMM_WORLD)
LibPETSc.DMSetType(petsclib, product, "product")
# Set the product 'topological' dimension to the number of component DMs
LibPETSc.DMSetDimension(petsclib, product, 2)
# Map product slots to sub-DM dimensions (index mapping); then attach sub-DMs
LibPETSc.DMProductSetDimensionIndex(petsclib, product, 0, 0)
LibPETSc.DMProductSetDimensionIndex(petsclib, product, 1, 0)
LibPETSc.DMProductSetDM(petsclib, product, 0, dm1)
LibPETSc.DMProductSetDM(petsclib, product, 1, dm2)

# Set up
LibPETSc.DMSetUp(petsclib, product)

# Cleanup
LibPETSc.DMDestroy(petsclib, product)
LibPETSc.DMDestroy(petsclib, dm1)
LibPETSc.DMDestroy(petsclib, dm2)

# Finalize PETSc and MPI
PETSc.finalize(petsclib)
MPI.Finalize()

DMRedundant

DMRedundant stores data redundantly across all processes, useful for small shared data.

DMComposite

DMComposite (deprecated, use DMProduct instead) manages multiple DMs as separate fields.

Functions

DMShell Functions

PETSc.LibPETSc.DMShellCreate — Method

dm::PetscDM = DMShellCreate(petsclib::PetscLibType,comm::MPI_Comm)

Creates a DMSHELL object, used to manage user

Collective

Input Parameter:

comm - the processors that will share the global vector

Output Parameter:

dm - the DMSHELL

Level: advanced

-seealso: DMDestroy(), DMCreateGlobalVector(), DMCreateLocalVector(), DMShellSetContext(), DMShellGetContext()

External Links