Re: [boost] [Review][PQS] Review deadline

From: John Phillips (phillips_at_[hidden])
Date: 2006-06-12 11:04:51

Leland Brown wrote:

> Janek Kozicki <janek_listy <at> wp.pl> writes:
> 
> 
>>Leland Brown said:     (by the date of Fri, 9 Jun 2006 04:31:28 +0000 (UTC))
>>
>>
>>>Actually, yes!  In fact, I played around quite a bit with allowing my 
> 
> matrix 
> 
>>>elements to be matrices themselves, and even implemented some of it. 
>>
>>wouldn't it be tensors, then?
> 
> 
> They act like partitioned matrices.  The elements are submatrices of the larger 
> matrix.  The same results can be obtained by putting all the individual scalar 
> elements into one big matrix, so there's not really any new functionality with 
> this, just notational convenience for some problems.
> 
> Tensors are a bit over my head, but I assume their semantics are different than 
> simply a partitioned matrix.  I don't think what I implemented would produce 
> tensor algebra.
> 
> -- Leland

   What it means to be a tensor is defined in terms of transformation 
properties. If the object transforms the proper way, it is a tensor, if 
not, it is not. Matrices may or may not be tensors, and certainly, many 
types of tensors can't be represented as simple matrices (since they can 
be more than 2 dimensional).
   The matrix elements are other matrices approach is something I've 
only used in the way Leland describes it. It is effectively a 
partitioning, and I have only used it in cases where it helps organize 
what I'm looking at. Maybe others have done other things with it.

                        John Phillips

> 
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