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Re: Two suggestions...
- From: "Robert G. Brown" <rgb at phy dot duke dot edu>
- To: Brian Gough <bjg at network-theory dot co dot uk>
- Cc: GSL Discussion list <gsl-discuss at sources dot redhat dot com>
- Date: Wed, 11 Jun 2003 14:39:21 -0400 (EDT)
- Subject: Re: Two suggestions...
On Wed, 11 Jun 2003, Brian Gough wrote:
> Robert G. Brown writes:
> > a) In relation to the recent discussion on multidimensional arrays,
> > what about adding gsl_tensor? Something like:
> >
> > typedef struct
> > {
> > size_t dim;
> > size_t stride;
> > size_t *size;
> > size_t *lind;
> > void * data;
> > gsl_block * block;
> > int owner;
> > } gsl_tensor;
>
> I agree that this is the right way to define a tensor object in
> principle.
>
> My concern about tensors is that it's difficult to do anything with
> the higher indices because all the blas/lapack routines only work for
> the last two indices.
>
> So it doesn't seem possible to create tensor views, which is part of
> the usefulness of the vectors and matrices.
Well, but there are spatial lattices and relativistic computations and
e.g. spin degrees of freedom in various dimensionalities where higher
dimensional objects than 2 occur all the time, so a lot of physics
would benefit from tensors (although yes, we can roll our own:-). In a
lot of these cases it isn't a matter of doing linear algebra per se that
is important (although in others it is -- so much so that it would be
lovely to be able to create a matrix or vector view of the tensor).
I'm in the process of experimenting with this. Let me see what I can
do. I'll try to keep my calls close enough to the gsl formats that
they'll be easy enough to port if it works out.
rgb
--
Robert G. Brown http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567 Fax: 919-660-2525 email:rgb@phy.duke.edu