Re: [boost] Re: Standard Matrix interfaces

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-08-23 02:41:31

----- Original Message -----
From: "Jeremy Siek" <jsiek_at_[hidden]>

> On Wed, 22 Aug 2001, David Abrahams wrote:
> david.>
> david.> I agree that it's a design question. Here's the scenario I'm
describing in
> david.> more detail:
> david.>
> david.> A matrix is not a linear operator by itself; it's more of
>
> Well, for convenience we'll probably want all the matrix classes to model
> LinearOperator (for matrix vector multiplication) in addition to being
> some sort of container.

That raises a (small) problem: given a matrix M, what does inverse(M) mean?
IOW, is inverse(M) the matrix inverse or is it just the inverse linear
operator?

Perhaps, since true matrix inversion is expensive, that ought to be called
matrix_inverse.

> david.> I guess what I'm trying to emphasize here is that the
> david.> factorization of a matrix is useful as a LinearOperator
> david.> but is not, by itself, a matrix in the usual sense.
>
> Right.

...and it ought to be seen as the inverse of the linear operator
corresponding to the matrix.

-Dave