# [Maxima] calculations involving matrices of matrices

Stavros Macrakis macrakis at alum.mit.edu
Tue Sep 16 06:23:03 CDT 2008

```You can't declare a variable to be explicitly a matrix, but you can

declare(x,nonscalar)

which has the same effect.

-s

On 9/16/08, Stanislav Maslovski <stanislav.maslovski at gmail.com> wrote:
> Hello,
>
> I would like to use matrices whose elements are matrices themselves.
> I see that I can do it in maxima, however I have two questions:
>
> 1. How can I tell maxima that an atom (not sure it is the correct term, let
> say a non-initialized variable) is a matrix?
>
> 2. If variables 'a', 'b', ... 'h' are matrices and
>
>     [a  b]       [e  f]
> A = [    ] , B = [    ]
>     [c  d]       [g  h]
>
> then A . B is calculated in maxima as
>
>         [a*e+b*g a*f+b*h]
> A . B = [               ]
>         [c*e+d*g c*f+d*h]
>
> (where the multiplications denoted by '*' are by element)
>
> I would like to do it rather as
>
>         [a.e+b.g a.f+b.h]
> A . B = [               ]
>         [c.e+d.g c.f+d.h]
>
> (where the multiplications are in matrix sense).
>
> Can I achieve this somehow?
>
> Thanks,
> --
> Stanislav
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