net.liuxuan.temp.mathtest.java Source code

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Here is the source code for net.liuxuan.temp.mathtest.java

Source

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package net.liuxuan.temp;

import java.util.ArrayList;
import java.util.List;
import org.apache.commons.math3.analysis.polynomials.PolynomialFunction;
import org.apache.commons.math3.fitting.CurveFitter;
import org.apache.commons.math3.fitting.PolynomialCurveFitter;
import org.apache.commons.math3.fitting.WeightedObservedPoint;
import org.apache.commons.math3.fitting.WeightedObservedPoints;
import org.apache.commons.math3.optim.nonlinear.vector.jacobian.LevenbergMarquardtOptimizer;

/**
 *
 * @author Moses
 */
public class mathtest {

    public static void main(String[] args) {

        final CurveFitter fitter = new CurveFitter(new LevenbergMarquardtOptimizer());
        fitter.addObservedPoint(-1.00, 2.021170021833143);
        fitter.addObservedPoint(-0.99, 2.221135431136975);
        fitter.addObservedPoint(-0.98, 2.09985277659314);
        fitter.addObservedPoint(-0.97, 2.0211192647627025);
        // ... Lots of lines omitted ...
        fitter.addObservedPoint(0.99, -2.4345814727089854);

        // The degree of the polynomial is deduced from the length of the array containing
        // the initial guess for the coefficients of the polynomial.
        final double[] init = { 12.9, -3.4, 2.1 }; // 12.9 - 3.4 x + 2.1 x^2

        // Compute optimal coefficients.
        final double[] best = fitter.fit(new PolynomialFunction.Parametric(), init);

        // Construct the polynomial that best fits the data.
        final PolynomialFunction fitted = new PolynomialFunction(best);
        System.out.println(fitted.value(-0.995));
        ;
        System.out.println(fitted.value(0.995));
        ;
        System.out.println(fitted.toString());
        ;
        System.out.println("=============================================================");
        PolynomialCurveFitter pcf = PolynomialCurveFitter.create(3);
        WeightedObservedPoints s;
        List<WeightedObservedPoint> points = new ArrayList<WeightedObservedPoint>();
        points.add(new WeightedObservedPoint(1, -1.00, 2.021170021833143));
        points.add(new WeightedObservedPoint(1, -0.99, 2.221135431136975));
        points.add(new WeightedObservedPoint(1, -0.98, 2.09985277659314));
        points.add(new WeightedObservedPoint(1, -0.97, 2.0211192647627025));
        points.add(new WeightedObservedPoint(1, 0.99, 2.4345814727089854));
        double a[] = pcf.fit(points);
        for (int i = 0; i < a.length; i++) {
            double d = a[i];
            System.out.println(d);
        }
        System.out.println(compute(a, -0.995));
        System.out.println(compute(a, 0.99));
        System.out.println(compute(a, 0.995));

    }

    public static double compute(double[] s, double in) {
        double y = 0;
        for (int i = 0; i < s.length; i++) {
            y += s[i] * Math.pow(in, i);
        }
        return y;
    }
}