Johan Hake wrote:
> On Monday 24 August 2009 09:08:49 Garth N. Wells wrote:
>> Johan Hake wrote:
>>> On Saturday 22 August 2009 14:02:06 DOLFIN wrote:
>>>> One or more new changesets pushed to the primary dolfin repository.
>>>> A short summary of the last three changesets is included below.
>>>>
>>>> changeset: 6833:30ddf63b8a1e25a6234703f1d47736ab90602376
>>>> tag: tip
>>>> user: "Garth N. Wells <[email protected]>"
>>>> date: Sat Aug 22 12:03:42 2009 +0100
>>>> files: dolfin/fem/VariationalProblem.cpp
>>>> dolfin/function/Function.cpp dolfin/function/Function.h
>>>> dolfin/function/SpecialFunctions.h
>>>> dolfin/function/SubFunctionData.h dolfin/function/dolfin_function.h
>>>> dolfin/swig/dolfin_docstrings.i dolfin/swig/dolfin_headers.i
>>>> description: Work on new sub Function logic.
>>> I am not sure we can completely wrap the new logic to PyDOLFIN.
>>>
>>> To be able to have the double inheritance of cpp.Function and
>>> ufl.Function in PyDOLFIN, new Functions have to be constructed in the
>>> Python interface (function.py).
>>>
>>> The operator[] is mapped to a hidden function _sub. The created Function
>>> that is returned from this is passed to the copy constructor in the
>>> Python version of sub (creating a new Function object). This is basically
>>> just how we did it before the new design, because previously operator[]
>>> returned a
>>> SubFunctionData, which was passed to a Function constructor. The
>>> transition to the new logic works in PyDOLFIN because the Function copy
>>> constructor is used instead of the removed SubFunctionData constructor.
>>>
>>> This means that the handy operator[], which returns a Function with a
>>> shared vector, cannot fully be used from PyDOLFIN. Would it be possible
>>> to add a shallow copy function in some way. Would this work with the
>>> present SubFunction design?
>> Would something like
>>
>> Function::sub_function(Function& sub_function, uint i)
>
> Yes I think so. If we could make this a constructor (shallow copy
> constructor)
> I would be most happy!
>
So a constructor
Function::Function(uint i)
would be better? I'm reluctant to add a constructor since it breaks the
paradigm that a Function constructor gives a deep copy. Could you create
an empty Function internally on the PyDOLFIN side and then pass it to
Function::sub_function(Function& sub_function, uint i)
to attach the shared data to create the sub-Function 'sub_function'?
Garth
> Johan
>
>> work?
>>
>> Garth
>>
>>> Johan
>>>
>>>> The new logic is more consistent with conventions.
>>>> Function::operator[](uint i) now returns a reference to the sub
>>>> Function. A Function keeps track of its sub Functions. Therefore,
>>>>
>>>> Function& u0 = u[0];
>>>>
>>>> and
>>>>
>>>> plot(u[0]);
>>>>
>>>> do not involve copying a vector. u and u0 share the same vector. If a
>>>> DofMap is renumbered after construction, the Function can make sure that
>>>> all its sub Functions are modified accordingly. Likewise if the mesh is
>>>> refined.
>>>>
>>>> Assignment makes a deep copy, i.e. you will get a new copy of
>>>> everything. Therefore with
>>>>
>>>> Function u0 = u[0];
>>>>
>>>> a new vector will be created and u0 will not change when u changes.
>>>>
>>>> What remains to be done is reseting the dof map for the reduced
>>>> dimension of the subfunction and extracting vector components upon
>>>> assignment. Eventually, for
>>>>
>>>> Function u0 = u[0];
>>>> GenericVector& x = u0.vector();
>>>>
>>>> the vector x will only contains components related to the sub function
>>>> u0.
>>>>
>>>>
>>>> changeset: 6832:887eaeeb4e81b30cf5e2031c77bd2d77f1faed18
>>>> user: "Garth N. Wells <[email protected]>"
>>>> date: Fri Aug 21 18:00:56 2009 +0100
>>>> files: dolfin/fem/DofMap.cpp
>>>> description:
>>>> Comment out duplicated code in DofMap.
>>>>
>>>>
>>>> changeset: 6831:da5b9081b7cbe9753b9ce833acffe0a9c6cac9e2
>>>> user: "Garth N. Wells <[email protected]>"
>>>> date: Fri Aug 21 17:23:38 2009 +0100
>>>> files: dolfin/log/LogStream.cpp dolfin/log/LogStream.h
>>>> dolfin/nls/NonlinearProblem.h description:
>>>> dolfin::cout fix for 32 bit systems.
>>>>
>>>> ----------------------------------------------------------------------
>>>> For more details, visit http://www.fenics.org/hg/dolfin
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