GAP Manual: 19.9. Value

Value( f, w )

Let f be a Laurent polynomial (..., f_(-1), f_0, f_1, ...). Then Value returns the finite sum ... + f_(-1) w^(-1) + f_0 w^0 + f_1 w + ....

Note that x need not be contained in the base ring of f.

    gap> x := Indeterminate(Integers);; x.name := "x";;
    gap> k := -x + 1;
    -x + 1
    gap> Value( k, 2 );
    -1
    gap> Value( k, [[1,1],[0,1]] );
    [ [ 0, -1 ], [ 0, 0 ] ]