dolfin team mailing list archive

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

Anders Logg wrote:
> On Mon, Aug 17, 2009 at 12:33:21PM +0100, Garth N. Wells wrote:
> > Please send any comments on how a SubFunction should work as I'm going
> > to work on it soon (the Cahn-Hilliard demo runs in parallel(!) ;) with
> > the exception of the extraction of sub-Functions for output). I'm
> > inlined to change a sub function such that for
> >
> >    Function u0 = u[0]
> >
> > the Function u0 will only point the vector belonging to u rather than
> > creating a new vector. The advantages are:
> >
> > - No need to copy a vector
> > - DofMap will not require 'is_view'
> > - Possible to do things like
> >     u0  = 0.0;
> >     u1  += v;
> >     u0.interpolate();
>
> Do all these only affect the part of the vector occupied by either u0
> or u1?

Yes, that's the idea.

Garth

> > Disadvantages are:
> >
> > - It may be unclear that u0 and u share data.
> > - If u goes out of scope, u0 is will keep the vector belonging to u
> > alive (only an issue if the vector is very large compared to that
> > required by u0).
>
> Sounds ok to me.
>
> --
> Anders
>
>
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