dolfin team mailing list archive

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

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?

> 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.

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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