Re: ublas : double * matrix

From: jhrwalter (walter_at_[hidden])
Date: 2002-01-17 09:58:25

--- In boost_at_y..., Toon Knapen <toon.knapen_at_s...> wrote:
> I noticed that in ublas 'a = 2 * b' works but 'a = b * 2' does 
not ?!

Meanwhile we've found two reasons for this restriction. First, as far 
as I know multiplication with a scalar is mathematically always 
defined as left multiplication for vectors and matrices. Next, 
multiplication is left associative in C++ (as Mathias told me ;-), so 
if we compare a = 2 * 2 * b to a = 2 * b * 2, the former is always 
guaranteed to need fewer operations.

Regards

Joerg