How to perform polyEval() ?

[pandasamanvaya]

Hi, everyone. I am new to HElib and recently tried to use the polyEval() function provided in the helib/polyEval.h header file. I tried to evaluate a simple polynomial x+x^2. But I am getting random values as output. Is there any documentation on how to use the polyEval()? Here is the code snippet -

#include<helib/helib.h>
#include<helib/polyEval.h>

using namespace std;
using namespace helib;

int main()
{
    //Defining CKKS scheme parameters
    Context context = ContextBuilder<CKKS>().m(16384).bits(119).precision(20).c(2).build();
    long n = context.getNSlots();

    //Generating keys
    SecKey secretKey(context);
    secretKey.GenSecKey();
    const PubKey& publicKey = secretKey;

    vector<int> x = {1, 2}, coeff={0, 1, 1};
    NTL::ZZX poly;
    for(int i=1; i < coeff.size(); i++){
        SetCoeff(poly, i, coeff[i]);
    }
    PtxtArray x0(context, x);
    Ctxt ct(publicKey);
    x0.encrypt(ct);

    Ctxt ans(publicKey);
    polyEval(ans, poly, ct);
    PtxtArray res(context);
    res.decrypt(ans, secretKey);

    vector<double> y;
    res.store(y);
    cout << y[0] << " " << y[1] << "\n";
}