Hallo!

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

r:=Rationals;
vars:=[];
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
well.

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
        Sergei

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