Derivative( f )
Let f be a Laurent polynomial (..., f_(-1), f_0, f_1, ...).
Then Derivative returns the polynomial g = (..., g_(i-1) = i*
f_i, ... ).
gap> x := Indeterminate(Rationals);; x.name := "x";;
gap> Derivative( x^10 + x^-11 );
10*x^9 - 11*x^(-12)
gap> y := Indeterminate(GF(5));; y.name := "y";;
gap> Derivative( y^10 + y^-11 );
Z(5)^2*y^(-12)