dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

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?

/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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> >>>
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> 
> 
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