Re: slicing and ranges of matrices

From: rwgk (rwgk_at_[hidden])
Date: 2002-01-21 19:05:28

--- In boost_at_y..., Toon Knapen <toon.knapen_at_s...> wrote:
> dynamic allocation will always involve a pointer dereference, 
would'nt it ?

Yes, but there is a difference in how you present it to
the user. IMO it is most convenient if the user is presented
with the same interface, irrespective of the details of
memory handling. To my knowledge this means the smart
pointer must be embedded inside the array class.
Also, generic functions for operations on arrays require
that the interfaces are identical.

> > My suggestions pertain only to dense arrays...
> 
> 
> even in that case, my remark still stands. E.g. for a 2D matrix, 
the 
> first index will always indicate the row, the second always the 
column, 
> independent of the aspect if the matrix is column-major or row-
major.

What is a row, what is a column?
When porting FORTRAN code to native C++ I needed a type
where the first index is the the "fast index"
and the second is the "slow index." Otherwise I would need
to torture my brain with rewriting all the algorithms.

> looks interesting but find it a pitty though that you're not using 
MTL 
> or ublas. I'm currently using ublas in my project and it works very 
> well. Apparantly you care a lot about memory handling (smart ptrs, 
> references .. ) but I think you can achieve all these with the 
current 
> libraries too.

Great. But why are you still looking at multi_array?
For me the answer is that I do not want a linear algebra
package but a versatile array handling package.
There seems to be a consensus that this needs to be
cleanly separated.

Ralf