CaRMtl/rene/zirkel/expression/Secant.java
2018-09-04 22:51:42 -04:00

65 lines
1.6 KiB
Java

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