PolynomialMethods.Factor() not working?

[archiecobbs]

I'm probably doing this wrong, but I can't get PolynomialMethods.Factor() to work correctly.

Test program:

import cc.redberry.rings.*;
import cc.redberry.rings.bigint.*;
import cc.redberry.rings.poly.*;
import cc.redberry.rings.poly.univar.*;
import cc.redberry.rings.poly.multivar.*;
import cc.redberry.rings.bigint.BigInteger;

import java.util.*;

public class FactorSums {

    // input consecutive coefficients starting with x^0
    public static void main(String[] args) throws Exception {
        final List<Integer> coeffs = new ArrayList<>(args.length);
        for (int i = 0; i < args.length; i++)
            coeffs.add(Integer.parseInt(args[i].replaceAll("[^0-9]", "")));
        final StringBuilder buf = new StringBuilder();
        for (int i = 0; i < args.length; i++) {
            final int coeff = coeffs.get(i);
            if (coeff == 0)
                continue;
            if (buf.length() > 0)
                buf.append("+");
            if (i > 0) {
                if (coeff > 1)
                    buf.append(coeff).append('*');
                buf.append("x");
                if (i > 1)
                    buf.append('^').append(i);
            } else
                buf.append(coeff);
        }
        System.out.println(" buf = " + buf);

        //final UnivariateRing<UnivariatePolynomialZp64> r = Rings.UnivariateRingZp64(p);
        final Integers z = Rings.Z;

        UnivariatePolynomial<BigInteger> poly = UnivariatePolynomial.parse(buf.toString(), z, "x");
        System.out.println("poly = " + poly);

        Object factors = PolynomialMethods.Factor(poly);
        System.out.println("factors = " + factors);

    }
}

Test input:

$ java FactorSums FactorSums 1 1 3 4 5 6 6 6 4
 buf = 1+x+3*x^2+4*x^3+5*x^4+6*x^5+6*x^6+6*x^7+4*x^8
poly = 1+x+3*x^2+4*x^3+5*x^4+6*x^5+6*x^6+6*x^7+4*x^8
factors = (1+x+3*x^2+4*x^3+5*x^4+6*x^5+6*x^6+6*x^7+4*x^8)

But 1+x+3*x^2+4*x^3+5*x^4+6*x^5+6*x^6+6*x^7+4*x^8 can actually be factored as (x+1)^2(3x^6+3x^4+2x^2+1) (at least, according to this).

I must be missing something...

[PoslavskySV]

Hi,

the polynomial is irreducible and 1+x+3*x^2+4*x^3+5*x^4+6*x^5+6*x^6+6*x^7+4*x^8 is not equal to (x+1)^2(3x^6+3x^4+2x^2+1). So, it seems that the link gives you a wrong result )

[archiecobbs]

Ah - actually it's my mistake, I entered the formula wrong on that website. Thanks & sorry for the noise.