> < ^ Date: Thu, 23 Sep 1999 13:58:30 +0200 (CEST)
> < ^ From: Sergei.Haller@math.uni-giessen.de < >
> ^ Subject: Matrices with arbitrary elements


I'm using GAP 4r1f2 and trying to operate with some matrices with
arbitrary elements. I'm defining them by

a:=Indeterminate(r, "a", vars);Add(vars, last);
b:=Indeterminate(r, "b", vars);Add(vars, last);
c:=Indeterminate(r, "c", vars);Add(vars, last);

m:=[[1,a],[0,1]]; # for example

The multiplication of such matreces with scalars, vectors and other
matreces, addition/subtraction with scalars and other matrices works very

But Inverse(m) or m^-1 (and all operations like m/m, which require m^-1)
don't work (but a^-1 does).
And [[1,a],[0,1]]*[[1,-a],[0,1]] returns [[1,0],[0,1]]

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

Why IsMatrix(m) returns false? (Of course, the elements of m are from
different families.)

But is there any way to make such computations?

Thank you for any information.

c ya

         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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