Pair.java

package jscl.math.polynomial.groebner;

import jscl.math.polynomial.Monomial;
import jscl.math.polynomial.Polynomial;

class Pair implements Comparable {
    final Polynomial polynomial[];
    final Monomial monomial[];
    final Monomial scm;
    final int sugar;
    boolean coprime;
    boolean reduction;
    Polynomial principal;

    Pair(Polynomial p1, Polynomial p2) {
        this(new Polynomial[]{p1, p2});
        coprime = monomial[0].gcd(monomial[1]).degree() == 0;
        int index[] = monomial[0].compareTo(monomial[1]) < 0 ? new int[]{0, 1} : new int[]{1, 0};
        reduction = monomial[index[1]].multiple(monomial[index[0]]);
        principal = polynomial[index[1]];
    }

    Pair(Polynomial polynomial[]) {
        this.polynomial = polynomial;
        monomial = new Monomial[]{polynomial[0].head().monomial(), polynomial[1].head().monomial()};
        scm = monomial[0].scm(monomial[1]);
        sugar = Math.max(polynomial[0].sugar() - polynomial[0].degree(), polynomial[1].sugar() - polynomial[1].degree()) + scm.degree();
    }

    public int compareTo(Pair pair) {
        int c = scm.compareTo(pair.scm);
        if (c < 0) return -1;
        else if (c > 0) return 1;
        else {
            c = polynomial[1].index() - pair.polynomial[1].index();
            if (c < 0) return -1;
            else if (c > 0) return 1;
            else {
                c = polynomial[0].index() - pair.polynomial[0].index();
                if (c < 0) return -1;
                else if (c > 0) return 1;
                else return 0;
            }
        }
    }

    public int compareTo(Object o) {
        return compareTo((Pair) o);
    }

    public String toString() {
        return "{" + polynomial[0].index() + ", " + polynomial[1].index() + "}, " + sugar + ", " + reduction;
    }
}