Re: [boost] Re: ublas : double * matrix

From: boost (boost_at_[hidden])
Date: 2002-01-21 05:11:21

Salut,

On Friday 18 January 2002 23:48, jhrwalter wrote:
> --- In boost_at_y..., Peter Schmitteckert (boost) <boost_at_s...> wrote:
[...]
> > BTW, is one allowed to use "non-commutative" scalars for ublas,
> > or is it implied that "a * b == b * a" ?
>
> To get usual linear algebra functionality, one should assume that the
> scalars form the approximation of a field. But I currently do not see
> any obvious reason, why one couldn't try to use a noncommutative
> multiplication for scalars. But then the approximations of vector
> space laws and linear operator properties may not hold.

A reason that one can't use non-commutative scalars could be
(compiler) optimizations that change the order of operands.

Best wishes,
Peter