A variable used to define polynomials.
%z
%z is the polynomial in the complex cases by default, z = poly(0, "z"). This variable is used to create polynomials.
z = poly(0, "z")
p = %z^2 + 2 * %i *%z -1 roots(p) coeff(p) z = poly(0, "z"); p1 = z^2 + 2*%i*z -1 roots(p1) coeff(p1)