dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Good point, but I don't see how to do this in DOLFIN without a few major
changes. For example, we assume that each vertex is associated to
exactly one coordinate and the local-to-global mappings that FFC
generate are computed in terms of the global number of vertices, edges etc.

Perhaps one could postprocess the system to remove the rows with a
single 1 on the diagonal (Dirichlet BCs) and the rows with a 1 and -1
(periodic BCs)?

/Anders


Matthew Knepley wrote:
> This seems weird to me. When I want periodic boundary conditions,
> I just make a periodic mesh. Anything else messes with the system
> too much. Making a periodic mesh from a flat one is simple surgery.
> I agree that you have to modify the computation of element geometry,
> but that seems to right place to me to account for the embedding.
>
>  Matt
>
> On 7/9/07, Garth N. Wells <g.n.wells@xxxxxxxxxx> wrote:
> > Quoting DOLFIN <dolfin@xxxxxxxxxx>:
> >
> > > One or more new changesets pushed to the primary dolfin repository.
> > > A short summary of the last three changesets is included below.
> > >
> > > changeset:   3306:c70033cb881cb98ef8f177ebf0cb95348de96aa7
> > > tag:         tip
> > > user:        "Anders Logg <logg@xxxxxxxxx>"
> > > date:        Mon Jul 09 19:24:50 2007 +0200
> > > files:       Makefile.in aclocal.m4 configure src/Makefile.in
> > > src/bench/Makefile.in src/bench/fem/Makefile.in 
> > src/bench/la/Makefile.in
> > > src/bench/ode/Makefile.in src/demo/Makefile.in src/greeting/Makefile.in
> > > src/kernel/Makefile.in src/kernel/common/Makefile.in
> > > src/kernel/common/dolfin/Makefile.in src/kernel/elements/Makefile.in
> > > src/kernel/elements/dolfin/Makefile.in 
> > src/kernel/fem/BoundaryCondition.cpp
> > > src/kernel/fem/Makefile.am src/kernel/fem/Makefile.in
> > > src/kernel/fem/PeriodicBoundaryCondition.cpp
> > > src/kernel/fem/dolfin/BoundaryCondition.h 
> > src/kernel/fem/dolfin/Makefile.am
> > > src/kernel/fem/dolfin/Makefile.in
> > > src/kernel/fem/dolfin/PeriodicBoundaryCondition.h
> > > src/kernel/fem/dolfin/dolfin_fem.h src/kernel/function/Makefile.in
> > > src/kernel/function/dolfin/Makefile.in src/kernel/graph/Makefile.in
> > > src/kernel/graph/dolfin/Makefile.in src/kernel/io/Makefile.in
> > > src/kernel/io/dolfin/Makefile.in src/kernel/la/Makefile.in
> > > src/kernel/la/dolfin/Makefile.in src/kernel/log/Makefile.in src/kernel
> > >  /log/dolfin/Makefile.in src/kernel/main/Makefile.in
> > > src/kernel/main/dolfin/Makefile.in src/kernel/math/Makefile.in
> > > src/kernel/math/dolfin/Makefile.in src/kernel/mesh/Makefile.in
> > > src/kernel/mesh/SubDomain.cpp src/kernel/mesh/dolfin/Makefile.in
> > > src/kernel/mesh/dolfin/SubDomain.h src/kernel/mf/Makefile.in
> > > src/kernel/mf/dolfin/Makefile.in src/kernel/nls/Makefile.in
> > > src/kernel/nls/dolfin/Makefile.in src/kernel/ode/Makefile.in
> > > src/kernel/ode/dolfin/Makefile.in src/kernel/parameter/Makefile.in
> > > src/kernel/parameter/dolfin/Makefile.in src/kernel/pde/Makefile.in
> > > src/kernel/pde/dolfin/Makefile.in src/kernel/plot/Makefile.in
> > > src/kernel/plot/dolfin/Makefile.in src/kernel/quadrature/Makefile.in
> > > src/kernel/quadrature/dolfin/Makefile.in src/lib/Makefile.in
> > > src/pydolfin/Makefile.in src/test/Makefile.in src/utils/Makefile.in
> > > src/utils/convert/Makefile.in src/utils/inp2dx/Makefile.in
> > > src/utils/swig/Makefile.in
> > > description:
> > > Add support for setting periodic boundary conditions.
> > >
> > > To set a periodic boundary condition, specify a pair of domains
> > > G and H by a SubDomain. The inside() function should specify the
> > > points of G and the map() function should specify a mapping F : H 
> > --> G.
> > >
> > > Then create a PeriodicBoundaryCondition and apply() it to the linear 
> > system.
> > >
> > > Bugs/features:
> > >
> > >   1. Only works for scalar subsystems, so it needs to be done once for
> > >   each subsystem of a vector function.
> > >
> > >   2. Setting the entries in the matrix can perhaps be optimized.
> > >
> > >   3. PeriodicBoundaryCondition is not a subclass of BoundaryCondition,
> > >   so it does not work to give a PeriodicBoundaryCondition as argument
> > >   to LinearPDE.
> > >
> > > To fix 3, should we rename BoundaryCondition --> DirichletBC
> > > and have PeriodicBC and DirichletBC as subclasses of BoundaryCondition?
> > >
> >
> > Yes, sounds good.
> >
> > Garth
> >
> > >
> > > changeset:   3305:4564fa57c9159e7dbe287ba121324ec84afd4d00
> > > user:        "Garth N. Wells <g.n.wells@xxxxxxxxxx>"
> > > date:        Thu Jul 05 22:24:27 2007 +0200
> > > files:       src/kernel/la/PETScLUSolver.cpp 
> > src/kernel/nls/NewtonSolver.cpp
> > > src/kernel/nls/dolfin/NewtonSolver.h src/kernel/pde/LinearPDE.cpp
> > > description:
> > > Fix use of PETSc with UMFPACK.
> > >
> > >
> > > changeset:   3304:1a95bb6095dd1b91e462f62a630035defd37c8c6
> > > parent:      3303:a324e9cb2c73b27ecd636fcee5b1a08cc01a0da8
> > > parent:      3302:cd19d9eeddaa68d14d8c6fafe4de490ff17c1f5a
> > > user:        "Garth N. Wells <g.n.wells@xxxxxxxxxx>"
> > > date:        Wed Jul 04 14:38:37 2007 +0200
> > > files:
> > > description:
> > > merge.
> > >
> > > ----------------------------------------------------------------------
> > > For more details, visit http://www.fenics.org/hg/dolfin
> > > _______________________________________________
> > > DOLFIN-dev mailing list
> > > DOLFIN-dev@xxxxxxxxxx
> > > http://www.fenics.org/mailman/listinfo/dolfin-dev
> > >
> > _______________________________________________
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