Java tutorial
/* GeoGebra - Dynamic Mathematics for Everyone http://www.geogebra.org This file is part of GeoGebra. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. */ /* * AlgoSimpleRootsPolynomial.java * * Created on 27.07.2010, 17:41 */ package geogebra.common.kernel.algos; import geogebra.common.kernel.Construction; import geogebra.common.kernel.EquationSolverInterface; import geogebra.common.kernel.Kernel; import geogebra.common.kernel.commands.Commands; import geogebra.common.kernel.geos.GeoElement; import geogebra.common.kernel.geos.GeoPoint; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import org.apache.commons.math.analysis.polynomials.PolynomialFunction; public abstract class AlgoSimpleRootsPolynomial extends AlgoIntersect { protected boolean setLabels; protected EquationSolverInterface eqnSolver; protected GeoElement[] geos; protected OutputHandler<GeoPoint> points; public AlgoSimpleRootsPolynomial(Construction c) { super(c); eqnSolver = cons.getKernel().getEquationSolver(); points = new OutputHandler<GeoPoint>(new elementFactory<GeoPoint>() { public GeoPoint newElement() { GeoPoint p = new GeoPoint(cons); // p.setCoords(0, 0, 1); p.setUndefined(); p.setParentAlgorithm(AlgoSimpleRootsPolynomial.this); return p; } }); } public AlgoSimpleRootsPolynomial(Construction c, GeoElement... geos) { this(c); this.geos = new GeoElement[geos.length]; for (int i = 0; i < geos.length; i++) { this.geos[i] = geos[i]; } setInputOutput(); } /** * @param pf * assigns a PolynomialFunction to this Algorithm which roots * lead to one or more output Points */ public void setRootsPolynomial(PolynomialFunction pf) { doCalc(pf); } public void setRootsPolynomialWithinRange(PolynomialFunction pf, double min, double max) { doCalc(pf, min, max); } @Override public GeoPoint[] getIntersectionPoints() { return points.getOutput(new GeoPoint[0]); } @Override protected GeoPoint[] getLastDefinedIntersectionPoints() { return null; } @Override protected void setInputOutput() { input = geos; setDependencies(); } /** * @param roots * array with the coefficients of the polynomial<br/> * the roots of the polynomial are assigned to the first n * elements of <b>roots</b> * @param eqnSolver * @return number of distinct roots */ public static int getRoots(double[] roots, EquationSolverInterface eqnSolver) { int nrRealRoots = eqnSolver.polynomialRoots(roots, false); // StringBuilder sb=new StringBuilder(); // for (int i=0;i<nrRealRoots;i++){ // if (i>0) // sb.append(','); // sb.append(roots[i]); // } // Application.debug("roots->"+sb); if (nrRealRoots > 1) { int c = 0; Arrays.sort(roots, 0, nrRealRoots); double last = roots[0]; for (int i = 1; i < nrRealRoots; i++) { if (roots[i] - last <= Kernel.MIN_PRECISION) { c++; } else { last = roots[i]; if (c > 0) roots[i - c] = roots[i]; } } nrRealRoots -= c; } return nrRealRoots; } protected void doCalc(PolynomialFunction rootsPoly) { double roots[] = rootsPoly.getCoefficients(); int nrRealRoots = 0; if (roots.length > 1) nrRealRoots = getRoots(roots, eqnSolver); makePoints(roots, nrRealRoots); } protected void doCalc(PolynomialFunction rootsPoly, double min, double max) { double roots[] = rootsPoly.getCoefficients(); int nrRealRoots = 0; if (roots.length > 1) nrRealRoots = getRoots(roots, eqnSolver); for (int i = 0; i < nrRealRoots; ++i) { if (Kernel.isGreater(roots[i], max, Kernel.STANDARD_PRECISION) || Kernel.isGreater(min, roots[i], Kernel.STANDARD_PRECISION)) roots[i] = Double.NaN; } makePoints(roots, nrRealRoots); } private static double distancePairSq(double[] p1, double[] p2) { return (p1[0] - p2[0]) * (p1[0] - p2[0]) + (p1[1] - p2[1]) * (p1[1] - p2[1]); } private void makePoints(double[] roots, int nrRealRoots) { List<double[]> valPairs = new ArrayList<double[]>(); int len; for (int i = 0; i < nrRealRoots; i++) { len = getNrPoints(roots[i]); for (int j = 0; j < len; j++) { double[] pair = getXYPair(roots[i], j); for (int k = 0; k < valPairs.size(); k++) { if (distancePairSq(pair, valPairs.get(k)) < Kernel.STANDARD_PRECISION) { pair = null; break; } } if (pair != null) valPairs.add(pair); } } setPoints(valPairs); } public void setLabels(String[] labels) { points.setLabels(labels); update(); } protected void setPoints(List<double[]> valPairs) { points.adjustOutputSize(valPairs.size()); for (int i = 0; i < valPairs.size(); i++) { points.getElement(i).setCoords(valPairs.get(i)[0], valPairs.get(i)[1], 1); } if (setLabels) points.updateLabels(); } /** * @param t * root of PolynomialFunction * @return number of corresponding outputPoints */ protected int getNrPoints(double t) { return 1; } /** * @param t * root of PolynomialFunction * @param idx * @return Y-value corresponding to t and idx. */ protected double getYValue(double t, int idx) { return getYValue(t); } /** * @param t * root of PolynomialFunction * @return the corresponding Y-value */ protected abstract double getYValue(double t); /** * @param t * root of PolynomialFunction * @return the corresponding X-value */ protected double getXValue(double t) { return t; } /** * @param t * root of PolynomialFunction * @param idx * @return X-value corresponding to t and idx. */ protected double getXValue(double t, int idx) { return getXValue(t); } protected double[] getXYPair(double t, int idx) { return new double[] { getXValue(t, idx), getYValue(t, idx) }; } @Override public Commands getClassName() { return Commands.Roots; } }