[pooma-dev] FieldStencils and Field(Range) views

[James Crotinger]

There is, in general, no good way to construct metric information for a
range view of a field, which is why range views evaluate to Fields with
NoGeometry. For instance, if you have a non-uniform non-orthogonal
coordinate system and you remove every other point in one direction, the new
mesh is no longer a simple sub-mesh of the old mesh, and there is no general
way for Pooma to calculate this new information. For fields with cartesian
coordinates this could be done, but such discrimination would have required
the coordinate system type to be a compile time quantity, and in the
re-design of Fields our main customers really wanted us to reduce the number
of template dependencies (helps code-bloat, compile time, . . .).

	Jim

> -----Original Message-----
> From: Nils H. Busch [mailto:nilsb at cns.mpg.de] 
> Sent: Friday, June 21, 2002 8:32 AM
> To: pooma-dev
> Subject: [pooma-dev] FieldStencils and Field(Range) views
> 
> 
> Hello,
> 
> I was trying to apply a FieldStencil on a view of a field 
> defined by a Range domain. I discovered that this does not 
> work, since such a view evaluates to a NoGeometry template 
> argument of Field. I was confirmed of this when reading the 
> tutorial. Does this mean, I cannot apply a FieldStencil to 
> Range views of fields ?
> 
> Is there a workaround to this or is this possible with Pooma 
> v 2.4 ? Currently, I am still using v 2.3, as I am not 
> certain whether work on v2.4 has been completed.
> 
> What I am trying to do, is to implement some kind of 
> reduction operation (for a multigrid scheme) that operates on 
> blocks of the finer resolution field and assigns them to a 
> coarser resolution field. If anyone could give me a hint on 
> how to approach that problem (what kind of classes to use, 
> example code that does similar things),  I would appreciate 
> it very much.
> 
> Thanks.
> 
> --
>     Nils H. Busch
>     Max-Planck-Institute of Cognitive Neuroscience
>     phone:  ++49 (341) 9940-035 fax:  ++49 (341) 9940-204
>     e-mail: nilsb at cns.mpg.de
> 
> 
> 
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