Java Number Power pow(double x, double y)

Description

pow

License

Open Source License

Declaration

public static final double pow(double x, double y) 

Method Source Code

//package com.java2s;

public class Main {
    public static final double pow(double x, double y) {
        return powTaylor(x, y);
    }//from   w w w  .  j  a v a 2 s .  c om

    private static final double powTaylor(double a, double b) {
        boolean gt1 = (Math.sqrt((a - 1) * (a - 1)) <= 1) ? false : true;
        int oc = -1, iter = 30;
        double p = a, x, x2, sumX, sumY;

        if ((b - Math.floor(b)) == 0) {
            for (int i = 1; i < b; i++)
                p *= a;
            return p;
        }

        x = (gt1) ? (a / (a - 1)) : (a - 1);
        sumX = (gt1) ? (1 / x) : x;

        for (int i = 2; i < iter; i++) {
            p = x;
            for (int j = 1; j < i; j++)
                p *= x;

            double xTemp = (gt1) ? (1 / (i * p)) : (p / i);

            sumX = (gt1) ? (sumX + xTemp) : (sumX + (xTemp * oc));

            oc *= -1;
        }

        x2 = b * sumX;
        sumY = 1 + x2;

        for (int i = 2; i <= iter; i++) {
            p = x2;
            for (int j = 1; j < i; j++)
                p *= x2;

            int yTemp = 2;
            for (int j = i; j > 2; j--)
                yTemp *= j;

            sumY += p / yTemp;
        }

        return sumY;
    }
}

Related

1. Pow(double val, Object in)
2. Pow(double value)
3. pow(double value)
4. pow(double x, double y)
5. pow(double x, double y)
6. pow(double x, int n)
7. pow(double[] array, double exp)
8. pow(double[][] x, int p)
9. pow(final double[] values, final double exp)