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

From: Toon Knapen (toon.knapen_at_[hidden])
Date: 2002-01-19 04:37:59

jhrwalter wrote:

>>>as I know multiplication with a scalar is mathematically always 
>>>defined as left multiplication for vectors and matrices. 
>>>
>>
>>theoretically scalar-matrix multiplication is commutative and thus 
>>
> a * M 
> 
>>== M * a.
>>
> 
> Hm. I'm not sure, if the rhs is defined at all.
> 

check out
boost/libs/numeric/doc/LinearAlgebraConcepts.html#VEctorSpace
for instance.

> 
> Division is another topic. We once discussed to introduce such a 
> division operator for accuracy reasons, although it's usually not 
> defined mathematically, too.
> 

what's the diff between M * ( 1 / a ) and M / a * 1

> 
>>Although I think in the long term, all mathematical correct 
> expressions 
>>should be supported but it is not highest priority.

agreed.