dolfin team mailing list archive

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

On Wed, 2006-03-29 at 16:27 -0600, Anders Logg wrote:
> On Thu, Mar 30, 2006 at 12:10:22AM +0200, Garth N. Wells wrote:
> 
> > > I'm not sure we should use Tensor or Array for this. They may have
> > > similarities in data structures (you can access entries in various
> > > positions) but I don't think they should have operations like inverse
> > > or eigenvalues.
> > > 
> > 
> > I was thinking more along the lines that Tensor would handle the
> > algebra, and DenseMatrix would be derived from it, with the
> > matrix-specific functions added in DenseMatrix.  Also, the current
> > Tensor template is really a multi-dimensional array. I think another
> > name like MultiDimensionalArray would be more appropriate once
> > tensor-valued functions are available.
> > 
> > Garth 
> 
> The class Tensor is not used anywhere. It was used before when the
> precomputation of integrals (tensor representation) was handled by
> DOLFIN. Since it has now moved to FFC, the class Tensor does not have
> any real use and could be removed. When I look at it now, it seems
> that I have assumed all axes have the same dimension, so you would
> only be able to create m x m matrices... :-) or waist the extra
> storage.
> 

OK.

> Another option would be to dig up the old DenseMatrix (attached) from
> before we removed it in version 0.5.5.
> 

I took a look at this earlier today. I thought that if we followed this
approach, it was worth considering an external library to cut down on
code and while offer the same or more features.

> But before we do anything more about this, it would be good to see
> some benchmarks to motivate why this can't be handled by PETSc. We use
> a lot of small PETSc matrices in the ODE solvers and it seems to work
> ok.
> 

I'll take a look. Are you creating PETSc dense matrices, or are you
using dolfin::Matrix?

Garth

> /Anders
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