varn symbolic variable of a polynomial or a rational [symb]=varn(p) [pm]=varn(p,varname) p matrix of polynomials or of rationals symb character string: name of the variable varname character string: the new name of the variable of p, set for pm pm matrix of polynomials or of rationals symb=varn(p) returns in symb the symbolic variable of the polynomial p (i.e. varn(poly(0,'x')) is 'x'). varn(p,'s') returns a polynomial matrix with same coefficients as p but with 's' as symbolic variable (change of variable name). poly rlist horner 5.5.1 Extension to rationals