how to get a polynomial eqn in variable i want ?

>>poly2sym([1 2 -1 1], s)

while using the poly2sym function as " >>poly2sym(c,y), " where c is the coeff. vector array ,i'm getting the error "undefined variable or func. y" , how do i get a pol. eqn . in variable i desire ?

Answer 1

[Star Strider]

Declare y as a symbolic variable first:

c = [1 2 -1 1];     % Polynomila Coefficients
syms y
poly2sym(c,y)

produces:

ans =

y^3 + 2*y^2 - y + 1