Various implementations of Netwon's method

kyle_newton.java

public ResultPair solveNewton(double init, double epsilon)
{
    int numIt = 1;
    double root;
    double xn;
    double xnPlusOne;
    double xnMinusOne;

    xn = init;
    xnPlusOne = xn - eval(xn) / getDeriv().eval(xn);

    while(Math.abs(xnPlusOne - xn) >= epsilon)
    {
        xn = xnPlusOne;
        xnPlusOne = xn - eval(xn) / getDeriv().eval(xn);
        numIt++;
    }

    root = xnPlusOne;
    ResultPair result = new ResultPair(root, numIt);

    return result;
}

zach_newton.java

public ResultPair solveNewton (double init, double epsilon)
{
    double[] x = new double[2]; // x_n and x_n+1, respectively
    int i;
    boolean finished = false;

    x[0] = init;

    for (i = 0; !finished ; i++)
    {
        // set x[n+1] by subtracting quotient of P(x[n]) and P'(x[n]) from x[n]
        x[1] = x[0] - (eval(x[0]) / getDeriv().eval(x[0]));

        // Check for root
        if (Math.abs(x[1] - x[0]) < epsilon)
        {
            finished = true;
        }

        x[0] = x[1];
    }

    return new ResultPair(x[1], i);
}