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On Thu, 23 Sep 1999, Sergei Haller wrote:

r:=Rationals;

vars:=[];

a:=Indeterminate(r, "a", vars);Add(vars, last);m:=[[1,a],[0,1]]; # for example ... Inverse(m) or m^-1 (and all operations like m/m, which require m^-1) don't work But [[1,a],[0,1]]*[[1,-a],[0,1]] returns [[1,0],[0,1]]

I have success if I define m as follows:

gap> m:=[[a^0,a],[0*a,a^0]]; [ [ 1, a ], [ 0, 1 ] ] gap> IsOrdinaryMatrix(m); # Now all matrix elements are from the same Family true gap> m^-1; [ [ 1, -a ], [ 0, 1 ] ] gap>

But this seems to be too complicate to do this. As said befroe,

multiplication, addition and subtraction work with m:=[[1,a],[0,1]] also.

Now is my Question: Is this the common way to define such matrices?

Is there any other way?

Thank you in advance.

c ya Sergei -------------------------------------------------------------------- eMail: Sergei.Haller@math.uni-giessen.de WWW-page: http://www.hrz.uni-giessen.de/~gc1007/ -------------------------------------------------------------------- The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny ..." -- Isaac Asimov

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