Re: [Axiom-mail] Setting elements in a matrix

[Martin Rubey]

"Fabio S." <address@hidden> writes:

> I am sorry, but I can't understand why I am not able to change the elements
> of a square matrix.

This is a consequence of SquareMatrix not inheriting from MatrixCategory.
Very likely, setelt was simply forgotten.

You have three possibilities:

a) 
  
  (6) -> setelt(n := (m::MATRIX INT), 1,1, 1783)
  
     (6)  1783
                                                          Type: PositiveInteger
  (7) -> n
  
          +1783  2+
     (7)  |       |
          + 3    4+
                                                           Type: Matrix Integer
  (8) -> m
  
          +1  2+
     (8)  |    |
          +3  4+
                                                  Type: SquareMatrix(2,Integer)
  
  So you will have to convert n back to SQMATRIX(2, INT).

b) make SQMATCAT inherit from MATCAT.  I have indicated how to do this on
   fricas-devel, I believe.  Unfortunately, my laptop with the appropriate
   modifications is currently broken, and will not be available until next
   week, I guess.  (Stupid me: the last version of the poset package is also on
   that laptop, along with several other things I miss a bit...)

   Very likely, this will only be easy in FriCAS, since you have to rebuild the
   databases from scratch.

c) wait for somebody else (me) to do (b).  I think it will be ready around
   easter or so.


Martin