Re: [Axiom-mail] Matrix algebra

[Ralf Hemmecke]

On 11/05/2007 08:05 AM, address@hidden wrote:
> For symbolic computation can Axiom recognize that matrix multiplication 
> in general does not commute, that is, for square matrices A and B, AB is 
> not (in general) equal to BA?
>
> Best regards,
>
> Erik Svensson    

Could you make your question more precise. I guess you already know what 
is given below.

Ralf


(1) -> m: Matrix(Integer) := matrix [[1,2],[3,4]]
        +1  2+
   (1)  |    |
        +3  4+
                                     Type: Matrix Integer
(2) -> n: Matrix(Integer) := matrix [[2,1],[3,4]]
(2) ->
        +2  1+
   (2)  |    |
        +3  4+
                                     Type: Matrix Integer
(3) -> m*n
(3) ->
        +8   9 +
   (3)  |      |
        +18  19+
                                     Type: Matrix Integer
(4) -> n*m
(4) ->
        +5   8 +
   (4)  |      |
        +15  22+
                                     Type: Matrix Integer
(5) -> n*m-m*n
(5) ->
        +- 3  - 1+
   (5)  |        |
        +- 3   3 +
                                     Type: Matrix Integer