65 lines
1.6 KiB
Java
65 lines
1.6 KiB
Java
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/*
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Copyright 2006 Rene Grothmann, modified by Eric Hakenholz
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This file is part of C.a.R. software.
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C.a.R. is a free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, version 3 of the License.
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C.a.R. is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package rene.zirkel.expression;
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import rene.zirkel.construction.ConstructionException;
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import rene.zirkel.objects.Evaluator;
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public class Secant {
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public static double compute(final Evaluator F, double a, double b,
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final double eps) throws ConstructionException {
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double ay = F.evaluateF(a), by = F.evaluateF(b);
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double c = (a + b) / 2;
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if (ay * by > eps)
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throw new ConstructionException("");
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while (Math.abs(b - a) > eps) {
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final double cy = F.evaluateF(c);
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if (Math.abs(cy) < eps)
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return c;
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if (cy * ay > 0) {
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if (Math.abs(ay - cy) < eps) {
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a = c;
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ay = cy;
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c = (a + b) / 2;
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} else {
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final double d = a - ay * (a - c) / (ay - cy);
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if (d > b || d < a) {
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a = c;
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ay = cy;
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c = (a + b) / 2;
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} else {
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a = c;
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ay = cy;
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c = d;
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}
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}
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} else {
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final double d = a - ay * (a - c) / (ay - cy);
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b = c;
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by = cy;
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c = d;
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}
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}
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return c;
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}
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}
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