Re: [ublas] multiarray subarray and matrix

Subject: Re: [ublas] multiarray subarray and matrix
From: Matwey V. Kornilov (matwey.kornilov_at_[hidden])
Date: 2010-04-02 14:09:04

Rhys Ulerich wrote:

>> It is interesting why no linear algebra library implements tensors with
>> rank greater than 2? At the same time I can't give a wide-known example
>> of high- rank tensor.
> 
> Not that anyone implements them this way, because it'd be silly, but
> the common transpose operation is a higher tensor:
> http://mathoverflow.net/questions/4167/what-are-the-components-of-a-
transpose-operator-from-rnn-to-rnn
> 

The more simple example is the Levi-Civita symbol and cross-product.

[ A x B ]_i = e_ijk A_j B_k

but it is a pure mathematical object. I meant that all known physical 
tensors are not of such high-rank.