dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Johan Jansson wrote:
> Anders Logg wrote:
> > On Mon, Dec 03, 2007 at 01:05:51AM +0100, DOLFIN wrote:
> >
> >   
> > > changeset:   3430:4fa0790a4fc34d3abac3079644368813a252ac61
> > > parent:      3428:7967082310c3ab03df9d812a6f471dcf988e7b4e
> > > user:        "Johan Jansson <jjan@xxxxxxxxxx>"
> > > date:        Sun Dec 02 20:17:50 2007 +0100
> > > files:       src/kernel/ode/MonoAdaptiveJacobian.cpp src/kernel/ode/MonoAdaptiveNewtonSolver.cpp src/kernel/ode/ODE.cpp src/kernel/ode/TimeSlabJacobian.cpp src/kernel/ode/dolfin/MonoAdaptiveJacobian.h src/kernel/ode/dolfin/MonoAdaptiveNewtonSolver.h src/kernel/ode/dolfin/ODE.h src/kernel/ode/dolfin/TimeSlabJacobian.h src/kernel/parameter/dolfin/DefaultParameters.h
> > > description:
> > > ODE:
> > >
> > > Added support for computing the Jacobian as a sparse matrix (only for
> > > mono-adaptive dG(0) and cG(1) so far, and only for PETSc).
> > >     
> > Why PETSc? The ODE solvers are tied to uBlas so the vectors won't be
> > parallel.
> >
> > How and when should this be used? Does it change anything in the
> > computation that the ODE solver does, or is it just a utility function
> > for computing the Jacobian that a user can call?
> >   
> Ideally the ODE solver should support both uBlas and PETSc, I think the 
> plan should be to transition to a general implementation if we start to 
> use it more for PDE. PETSc has a higher priority than uBlas though, 
> since that's what we use for large computations (due to efficiency and 
> robustness), and since it's parallel while uBlas is not.

Why don't you try to implement it through the common interface?  We'll 
soon have more linear algebra back-ends (e.g. Trilinos).

Garth

> The sparse Jacobian matrix is used in the mono-adaptive Newton case when 
> the option "ODE matrix-free jacobian" is set to false. The way I've 
> implemented time-dependent PDE with the ODE solver is that the form for 
> the Jacobian is supplied, and a TimeDependentPDE class provides ODE::J() 
> and ODE::Jmatrix() based on this form.
>
>   Johan
>
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