ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

ok.

Is this documented in the manual? It made me confused the first time I
saw it. Otherwise it's a good example to add.

-- 
Anders


On Tue, Apr 07, 2009 at 06:42:28PM +0200, Martin Sandve Alnæs wrote:
> Yes.
> 
> grad(u).T*u
> =
> dot(grad(u).T, u)
> =
> dot(u, grad(u))
> 
> Martin
> 
> 
> 
> On Tue, Apr 7, 2009 at 6:40 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> > On Tue, Apr 07, 2009 at 05:19:42PM +0200, Martin Sandve Alnæs wrote:
> >> On Tue, Apr 7, 2009 at 5:17 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> >> > On Tue, Apr 07, 2009 at 02:48:44PM +0200, UFL wrote:
> >> >> One or more new changesets pushed to the primary ufl repository.
> >> >> A short summary of the last three changesets is included below.
> >> >>
> >> >> changeset:   811:b96d2bbe8284a7255ca510c2fbb35b1445f85a11
> >> >> tag:         tip
> >> >> user:        "Martin Sandve Alnæs <martinal@xxxxxxxxx>"
> >> >> date:        Tue Apr 07 14:50:30 2009 +0200
> >> >> files:       doc/manual/chapters/formlanguage.tex ufl/operators.py
> >> >> description:
> >> >> Added support for this syntax:
> >> >>
> >> >> x = cell.x
> >> >> Df = diff(f, x)
> >> >>
> >> >> Note that
> >> >>   diff(f, x) == grad(f).T
> >> >> because of the way diff is defined.
> >> >> Thus diff(f,x) is the same as the FFC grad.
> >> >> If we want to change this, it touches a lot
> >> >> of places in AD code, so that won't happen now.
> >> >
> >> > How should the Navier-Stokes convective term be expressed in UFL?
> >> >
> >> > I guess one needs to write
> >> >
> >> >  grad(u).T*u
> >> >
> >> > ?
> >>
> >> Like you write it on paper:
> >>
> >> w . grad u = dot(w, grad(u))
> >>
> >> And:
> >>
> >> w . grad u . v = dot(dot(w, grad(u)), v)
> >
> > Yes, but does
> >
> >  grad(u).T*u
> >
> > also work?
> >
> >
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> >
> >

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