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Java Newton's Method HELP PLEASE

Hey I'm a total beginner to Java and I could really use some help with this program please!
This is part of the code I wrote. I put a do-while loop but this only takes care of the rootEstimate value, the powerRider value is also changing. Basically I need to end up with my answer for the root Estimate then after I got the answer with the first power, switch to the second power. The powerRider variable is declared as an array. I was thinking of possibly having a loop with an increment encasing the do-while loop which would increase whenever the while part is not met, but I'm not 100% sure how to approach this and some help would be appreciated!

Code:

 function = -n*powerRider + 0.5*(rho*cD*area*(Math.pow(initialRootEstimate,3))) + (cR*m*g*initialRootEstimate);

 derivedFunction = (3/2)*(rho*cD*area*(Math.pow(initialRootEstimate,2))) + (cR*m*g);

 do

 {

  rootEstimate = initialRootEstimate - (function/derivedFunction);

  absDifference = Math.abs(rootEstimate-initalRootEstimate);

  numLoops++;

  initialRootEstimate=rootEstimate;

  }

Thank you!

Re: Java Newton's Method HELP PLEASE

post the mathematics problem you are trying to solve.

Re: Java Newton's Method HELP PLEASE

i m sending u a newton class..post ur sum...will let u know d solution...

Code:

class Newton  {



    static double f(double x) {

        return Math.sin(x);

    }



    static double fprime(double x) {

        return Math.cos(x);

    }



    public static void main(String argv[]) {



          double tolerance = .000000001; // Our approximation of zero

          int max_count = 200; // Maximum number of Newton's method iterations



/* x is our current guess. If no command line guess is given, 

   we take 0 as our starting point. */



          double x = 0;



          if(argv.length==1) {

            x= Double.valueOf(argv[0]).doubleValue();

          }



         for( int count=1;

                  (Math.abs(f(x)) > tolerance) && ( count < max_count);

                 count ++)  {

            x= x - f(x)/fprime(x);

            System.out.println("Step: "+count+" x:"+x+" Value:"+f(x));

          }            



          if( Math.abs(f(x)) <= tolerance) {

           System.out.println("Zero found at x="+x);

          }

          else {

           System.out.println("Failed to find a zero");

          }

     }



}

Re: Java Newton's Method HELP PLEASE

Hey sorry I've been working on it so haven't had a chance to check back. Thanks for the help! So far I've written this:

Code:

import java.io.*;



public class Assignment1try2



{



    public static void main(String[] args)



    {

        //Exports the data to an excel file



     PrintWriter outputFile = null;

       try

         {

           outputFile = new PrintWriter(new FileOutputStream("outputVelomobile.xls",false));

          }

            catch(FileNotFoundException e)

         {

           System.out.println("File error.  Program aborted.");

           System.exit(0);

          }





        //Variable declarations for the Quest Velomobile



    double n = 0.92;

    double rho = 1.20;

    double cR = 0.004;

    double m = 32+80;

    double g = 9.81;

    double cD = 0.24;

    double area = 0.46;

    double valueOne = rho*cD*area;

    double valueTwo = cR*m*g;

    double initialRootEstimate = 1;

    double function, absDifference;

    double[] rootEstimate = new double[8];

    int numLoops = 0;

    int[] powerRider = {25,50,75,100,150,200,300,400};





        //Start loop

    for (int index=0;index<powerRider.length;index++)



    {



         numLoops = 0;



        do

        {



        function = -n*powerRider[index] + 0.5*(valueOne*(Math.pow(initialRootEstimate,3))) + (valueTwo*initialRootEstimate);



        rootEstimate[index] = initialRootEstimate - (function/((3/2)*(valueOne*(Math.pow(initialRootEstimate,2))) + (valueTwo)));



        absDifference = Math.abs(rootEstimate[index] - initialRootEstimate);



        initialRootEstimate = rootEstimate[index];

        numLoops++;



         }



           while (absDifference >=1.0E-12);



            //Displays data on screen

            System.out.println();

            System.out.println("The Power is:"    +   powerRider[index]);

            System.out.println("The Root Estimate is:"    +   initialRootEstimate);

            System.out.println("The number of cycles is:"    +   numLoops);

            System.out.println();



            //Outputs results on screen



            outputFile.println();

            outputFile.println("The Power is:"    +   powerRider[index]);

            outputFile.println("The Root Estimate is:"    +   initialRootEstimate);

            outputFile.println("The number of cycles is:"    +   numLoops);

            outputFile.println();





        }

            outputFile.close();

    }



}

It works but the only problem is that we end up with a lot of iterations. Is there any way we can reduce the amount of iterations?

thanks again