pow approximation with exponentiation by squaring

public static double pow(final double a, final double b) {
    // exponentiation by squaring
    double r = 1.0;
    int exp = (int) b;
    double base = a;
    while (exp != 0) {
        if ((exp & 1) != 0) {
            r *= base;
        }
        base *= base;
        exp >>= 1;
    }

    // use the IEEE 754 trick for the fraction of the exponent
    final double b_faction = b - (int)b;
    final long tmp = Double.doubleToLongBits(a);
    final long tmp2 = (long) (b_faction * (tmp - 4606921280493453312L)) + 4606921280493453312L;
    return r * Double.longBitsToDouble(tmp2);
}