Question for the math lovers! Using while loop and exponents

Question

Hi there Java geniuses! ; ) A little question here that has been perplexing me for the past few days. I'm trying to create a class that contains a single static method as follows:
public static double exp(double a)
It's supposed to work to calculate an "exp" value much like the Math.exp method of the Math class. Essentially, I need to keep calculating approximations of "exp" until a certain condition is met. This condition is specified in a while loop. Following is what I've written so far. But I can't seem to get the thing to work properly. Any suggestions/ advice would be greatly appreciated! Thanks.
A class that computes the "exp" for a user-defined
value.
public class MyMath
public static double exp(double x)
double dbloldGuess;
double dblnewGuess = 1 + x; // First value for newGuess
double dblcounter = 1;
do
dblcounter++; // increments counter
dbloldGuess = dblnewGuess;
dblnewGuess = dbloldGuess + ((x ** dblcounter) / counter);
while (Math.abs((newGuess - oldGuess) / newGuess) > 1e-15);
return x;
}

Answer 1

** wasn't an operator in C when I last checked...
Anyway here's my lousy attempt:public static double exp(double a) {
        double guess = 1;
        int N = 18;
        while (N --> 1) guess = 1 + a/N * guess;
        return guess;
}When called with 1.0 as argument gives the value equal to the constant Math.E, so is "probably" ok for arguments 0.0 -- 1.0. I wont guarantee anything else because this method is pretty pathological when it comes to loss of precision due to rounding, even if you increase N.