001/*
002 * $Id: ElementaryIntegrationBernoulli.java 5999 2020-03-17 15:44:50Z kredel $
003 */
004
005package edu.jas.integrate;
006
007
008import java.util.ArrayList;
009import java.util.List;
010
011import org.apache.logging.log4j.LogManager;
012import org.apache.logging.log4j.Logger;
013
014import edu.jas.poly.AlgebraicNumber;
015import edu.jas.poly.GenPolynomial;
016import edu.jas.poly.GenPolynomialRing;
017import edu.jas.structure.GcdRingElem;
018import edu.jas.structure.RingFactory;
019import edu.jas.ufd.FactorAbsolute;
020import edu.jas.ufd.PartialFraction;
021
022
023/**
024 * Methods related to the Bernoulli algorithm for elementary integration. The
025 * denominator is factored into linear factors over iterated algebraic
026 * extensions over the rational numbers.
027 * 
028 * @author Heinz Kredel
029 * @param <C> coefficient type
030 */
031
032public class ElementaryIntegrationBernoulli<C extends GcdRingElem<C>> extends ElementaryIntegration<C> {
033
034
035    private static final Logger logger = LogManager.getLogger(ElementaryIntegrationBernoulli.class);
036
037
038    //private static final boolean debug = logger.isDebugEnabled();
039
040
041    /**
042     * Constructor.
043     */
044    public ElementaryIntegrationBernoulli(RingFactory<C> br) {
045        super(br);
046        if (!(irr instanceof FactorAbsolute)) {
047            logger.error("no absolute factorization available for coefficient ring " + br);
048            throw new IllegalArgumentException(
049                            "no absolute factorization available for coefficient ring " + br);
050        }
051        irredLogPart = true; // force to true?
052    }
053
054
055    /**
056     * Univariate GenPolynomial integration of the logarithmic part, Bernoulli
057     * linear factorization algorithm.
058     * @param A univariate GenPolynomial, deg(A) < deg(P).
059     * @param P univariate squarefree or irreducible GenPolynomial. // gcd(A,P)
060     *            == 1 automatic
061     * @return logarithmic part container.
062     */
063    @Override
064    public LogIntegral<C> integrateLogPart(GenPolynomial<C> A, GenPolynomial<C> P) {
065        if (P == null || P.isZERO()) {
066            throw new IllegalArgumentException("P == null or P == 0");
067        }
068        //System.out.println("\nP_base_algeb_part = " + P);
069        GenPolynomialRing<C> pfac = P.ring; // K[x]
070        if (pfac.nvar > 1) {
071            throw new IllegalArgumentException("only for univariate polynomials " + pfac);
072        }
073        // pfac.coFac.isField() by FactorAbsolute
074        List<C> cfactors = new ArrayList<C>();
075        List<GenPolynomial<C>> cdenom = new ArrayList<GenPolynomial<C>>();
076        List<AlgebraicNumber<C>> afactors = new ArrayList<AlgebraicNumber<C>>();
077        List<GenPolynomial<AlgebraicNumber<C>>> adenom = new ArrayList<GenPolynomial<AlgebraicNumber<C>>>();
078        // P linear
079        if (P.degree(0) <= 1) {
080            cfactors.add(A.leadingBaseCoefficient());
081            cdenom.add(P);
082            return new LogIntegral<C>(A, P, cfactors, cdenom, afactors, adenom);
083        }
084        // complete factorization to linear factors
085        PartialFraction<C> F = ((FactorAbsolute<C>) irr).baseAlgebraicPartialFraction(A, P);
086        //System.out.println("\npartial fraction " + F);
087
088        return new LogIntegral<C>(A, P, F.cfactors, F.cdenom, F.afactors, F.adenom);
089    }
090
091}