dolfin team mailing list archive

[Kristian Oelgaard <k.b.oelgaard@xxxxxxxxxx>]

Quoting Marie Rognes <meg@xxxxxxxxxxx>:

> Garth N. Wells wrote:
> >
> >
> > Jed Brown wrote:
> >> On 11 Mar 2008, meg@xxxxxxxxxxx wrote:
> >>
> >>> After diving into some non-linear elasticity, I've suddenly the need to
> >>> do u^k, that is u to the power k, where u is some Function and k is 
> >>> an arbitrary natural number.
> >>
> >> I actually need this when k is not an integer which means that it cannot
> >> be done exactly, even with enough quadrature points.  For the case when
> >> k is an integer greater than 2, it is likely not desirable to perform
> >> the integration exactly because it entails too many quadrature points
> >> (perhaps for k=2 as well) so my understanding is that you must make a
> >> separate form to computes the nonlinear part.
> >>
> >
> > The best way to do this will be to use quadrature. With the quadrature 
> > option you can specify the number of integration points you want to 
> > use.  Also, you'll can generate a correct linearisation. Kristian is 
> > currently working on some optimisations of quadrature code, after 
> > which we will add some illustrative demos.
> >
> 
> Ok. Excellent!

This might not happen in the nearest future, but there should be something in
the FFC manual about the QuadratureElement and how it can be used to solve a
non-linear problem.

Kristian
 
> -- 
> Marie E. Rognes
> Ph.D Fellow, 
> Centre of Mathematics for Applications, 
> University of Oslo
> http://folk.uio.no/meg
> 
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