Re: BZDEV: Extension to stride

[Todd V. <tve...@ex...>]

>    Stride is a good idea. But it can be extended.
>    Many algorithms that need a pivot, require to swap rows or columns.
> Thus can be taken care
> by using an array that tells how the rows or columns are ordered. While
> accessing these can be a small
> overhead, I think it might save on moving and copying data. Especially
> if it is a derived class.
> swap_included_array -> array
>   What do you think

You can do this in a limited way with Cartesian-product 
indirection.  See 

http://oonumerics.org/blitz/manual/blitz06.html#index00411

The limitation is that the permuted array can only be used as
an lvalue (on the left side of an assignment).  If someone needs
to use it as an rvalue I'd be willing to think about how to do
that.

All the algorithms I've seen which require pivots are linear
algebra, and might be easier to express in libraries like MTL
or SL, which have been designed for linear algebra.

Cheers,
Todd

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