dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Fri, Mar 09, 2007 at 07:10:31PM +0100, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > On Fri, Mar 09, 2007 at 03:07:43PM +0100, Garth N. Wells wrote:
> > > > Why do we need a class AssemblyMatrix? GenericMatrix/GenericVector 
> > > > should provide the necessary  virtual functions for assembly.
> > > >
> > > > Garth
> > > Yes, definitely. The assembler assumes it gets a GenericTensor that
> > > has a function
> > >
> > >     void add(real* block, uint* size, uint** entries)
> > >
> > > (entries is probably a bad choice of name here, let's change it)
> > > This makes it possible to implement just one assembly function and
> > > keep the Assembler class small.
> > Then GenericVector and GenericMatrix should then derive from GenericTensor?
>
> Yes. So far it is just two functions that are needed, init() and add().
>
> > > Anyway, the class AssemblyMatrix is just a temporary implementation of
> > > something that implements the GenericTensor interface. My suggestion
> > > is that we overload the add() function above in both GenericMatrix and
> > > GenericVector. The overloaded functions will map to the correct add()
> > > function in the respective classes. For GenericMatrix, we'll have
> > >
> > >     void add(real* block, uint* size, uint** entries)
> > >     {
> > >         add(block, size[0], entries[0], size[1], entries[1]);
> > >     }
> > >
> > > So, even if AssemblyMatrix could be of some use (it seems to be a fast
> > > option for assembly, the STL vector of maps beat PETSc in at least one
> > > benchmark I made) 
> > Don't draw conclusions too quickly. STL vector of maps is fast to 
> > assemble, but is close to useless for linear algebra. The current 
> > implementation for the assembly uBLAS matrices use something like STL 
> > vector of maps  (fast to assemble but slow for linear algebra) and 
> > converts it to compressed row storage (fast for linear algebra). The 
> > conversion can take some time. A STL vector of integer maps should be 
> > created and then used to initialise a particular sparse storage format 
> > (before first use only). Then we wouldn't have to convert matrix formats.
>
> Do you mean this should be done in DofMap?

Yes. The STL vector of maps is cheap to construct, and can be used to 
initialise the non-zero layout of a sparse matrix.

Garth.

> /Anders
>
> > Garth
> >
> > it is just a temporary implementation until we decide
> > > to implement the GenericTensor interface in GenericMatrix and
> > > GenericVector.
> > >
> > > /Anders
> > >
> > > > DOLFIN wrote:
> > > > > One or more new changesets pushed to the primary DOLFIN repository.
> > > > > A short summary of the last three changesets is included below.
> > > > >
> > > > > changeset:   2698:eb995ba168f6249aa061bf16b6b094d7d697090b
> > > > > tag:         tip
> > > > > user:        "Anders Logg <logg@xxxxxxxxx>"
> > > > > date:        Fri Mar 09 13:40:42 2007 +0100
> > > > > files:       TODO src/kernel/fem/Assembler.cpp src/kernel/fem/UFC.cpp src/kernel/fem/dolfin/UFC.h src/sandbox/assembly/Poisson.form src/sandbox/assembly/Poisson.h src/sandbox/assembly/PoissonOld.form src/sandbox/assembly/PoissonOld.h src/sandbox/assembly/main.cpp
> > > > > description:
> > > > > Implement assembly over interior facets. The result seems to
> > > > > be wrong (compared to the old assembly) but the new assembly
> > > > > is considerably faster... :-)
> > > > >
> > > > >
> > > > > changeset:   2697:d9af2a3e540db91dc68936ff188c588b0cc259e9
> > > > > parent:      2696:e7e54e87c948b580979f1041facb491e5dacd102
> > > > > parent:      2695:1099832e1b156f53450783a81243609beab71fff
> > > > > user:        "Anders Logg <logg@xxxxxxxxx>"
> > > > > date:        Fri Mar 09 09:17:50 2007 +0100
> > > > > files:       src/kernel/la/PETScEigenvalueSolver.cpp src/kernel/la/dolfin/PETScEigenvalueSolver.h
> > > > > description:
> > > > > Merge assembly over exterior facets
> > > > >
> > > > >
> > > > > changeset:   2696:e7e54e87c948b580979f1041facb491e5dacd102
> > > > > parent:      2690:24a6d6a566cdbdccb2c253cc62522fd265dad1af
> > > > > user:        "Anders Logg <logg@xxxxxxxxx>"
> > > > > date:        Thu Mar 08 23:30:09 2007 +0100
> > > > > files:       src/kernel/fem/Assembler.cpp src/sandbox/assembly/Poisson.form src/sandbox/assembly/Poisson.h src/sandbox/assembly/main.cpp
> > > > > description:
> > > > > Implement assembly over exterior facets (interior facets remain).
> > > > >
> > > > >
> > > > > ----------------------------------------------------------------------
> > > > > For more details, visit http://www.fenics.org/hg/dolfin
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