dolfin team mailing list archive

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

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();

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).

Garth