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