[jhetfield18]

Hi,I'm having a very strange problem.I have written code for an exercise that calculates the square root of a number either by asking the user for input or by giving it as argument when running the prog using Newtons method(a method I must create) and Math.sqrt and printing the results to see if they are the same.That is done.The next exercise is to tamper with the code and add a method that fills an array X(declared on the top) random integers so that another method I have to create will again use Math.sqrt and Newton so that it can measure the milliseconds in execution and print which method is faster.Only when I use start=System.currentTimeMillis(),the value stored in start is like this:1.193772081281E12 and is the same in both start and end variables even if i have a for() in between.And as a result it gives 0.00 ms.



Here is my code:

Code:

package sroot2;
import java.io.*;
import java.util.Random;
public class SRoot2 {
	public static int i;
	public static Random random = new Random();
	public final static int X=1000;
	public static double[] numbers=new double[X];
	public static double startNewton=0, endNewton=0, startMath=0, endMath=0, timeNewton=0, timeMath=0;
	
	//Here we declare the two variables that will help us get the input from the user
	//and parse it into an integer.
	static public InputStreamReader input = new InputStreamReader(System.in);
	static public BufferedReader keyboardInput = new BufferedReader(input);
	
	public static void main(String[] args) throws IOException {
		//If the string array is empty(meaning that no arguments were given upon launch of the program),
		//the inputdatainteger variable calls the readline function to get an input from the user and 
		//return an integer value.Then the program runs the same way as if args wasn't empty but only for
		//one value at a time.Also the program asks repeatedly for more inputs from the user until the latter
		//gives 0 for input.
		if(args.length==0){
			double inputdatainteger=readLine();
		 	while(inputdatainteger!=0){
		 		double NewtonResUs=Newtonsqrt(inputdatainteger,1);
		 		double MathResUs=Math.sqrt(inputdatainteger);
		 		double VariationUs=Math.abs(MathResUs-NewtonResUs);
		 		System.out.println("Number:"+Math.round(inputdatainteger));
		 		System.out.println("SRoot(Newton):"+Math.round(NewtonResUs));
		 		System.out.println("SRoot(Java Math):"+Math.round(MathResUs));
		 		System.out.println("Variation:"+Math.round(VariationUs));
		 		System.out.println("--------------------------------------");
		 		inputdatainteger=readLine();
		 	}
		}
		else{
			//If the string array is not empty it runs as SRoot.
	     double[] argumentsdouble = new double[args.length];
	     double[]  NewtonResults= new double[args.length];
	     double[]  MathResults= new double[ args.length];
	     double[]  Variation= new double[args.length];
	         for(i=0;i<args.length;i++){
	        	 argumentsdouble[i] = Double.parseDouble(args[i]);
	             if(argumentsdouble[i]>0){
	            	 MathResults[i]=Math.sqrt(argumentsdouble[i]);
	            	 NewtonResults[i]=Newtonsqrt(argumentsdouble[i],1);
	                 Variation[i]=Math.abs(MathResults[i]-NewtonResults[i]);
	             }
	             else{
	            	 NewtonResults[i]=MathResults[i]=-1;
	             }
	         }
	         for(i=0;i<argumentsdouble.length;i++){
	        	 System.out.println("Number:"+Math.round(argumentsdouble[i]));
	        	 if(argumentsdouble[i]<0){
	        		 System.out.println (argumentsdouble[i]+" ERROR: Non-positive number");
	        		 System.out.println("--------------------------------------");
	        	 }
	        	 else{
	        		 System.out.println("SRoot(Newton):"+Math.round(NewtonResults[i]));
	        		 System.out.println("SRoot(Java Math):"+Math.round(MathResults[i]));
	        		 System.out.println("Variation:"+Math.round(Variation[i]));
	        		 System.out.println("--------------------------------------");
	        	 }
	         }
		}
		fillRandom(numbers);
		executionTimeStatistics(numbers);
	}
	//The function that calculates the square root of a given number using Newton's method.
	//It runs by using the guess and the number recursively until the difference between the
	//x and newx is smaller than the threshold.Which means that we have more or less found the square root. 
	 public static double Newtonsqrt(double B,double x){
	     double newX;
	    
	     double threshold = 0.1;
	     
	     newX = 0.5 * (x + B / x);
	     
	     if (Math.abs(x - newX) > threshold) {
	         newX = Newtonsqrt(B, newX);
	     }
	     
	     return newX;
	 }
	 //This function reads the input from the keyboard and parses it(as it is a string) into an integer
	 //before returning it for storage.
	 public static double readLine() throws IOException{
		System.out.print("Input an integer: ");
	    String ss = keyboardInput.readLine();
	    double inputdatainteger = Double.parseDouble(ss);
	    return inputdatainteger;
	 }
	public static void fillRandom(double[] numbers){
		int rn=Math.abs(random.nextInt(300));
		 for(i=0;i<X;i++){
			 numbers[i]=(double)rn;
			 rn=Math.abs(random.nextInt(300));
		 }
	 }
	public static void executionTimeStatistics(double[] numbers){
		startNewton = System.currentTimeMillis();
			for(i=0;i<X;i++){
				Newtonsqrt(numbers[i],1);
			}
		endNewton = System.currentTimeMillis();
		System.out.println(startNewton+" "+endNewton);
		//timeNewton=endNewton-startNewton;		
		startMath = System.currentTimeMillis();
		for(i=0;i<X;i++){
			Math.sqrt(numbers[i]);
		}
		endMath = System.currentTimeMillis();
		timeMath=endMath-startMath;
		System.out.print("Statistics for "+X+" computations.\nExecution time using Newton: "+timeNewton+" ms.\nExecution time using Math: "+timeMath+" ms.\n");
		if(timeMath<timeNewton){
			System.out.print("The winner is Java.Math.\n");
		}
		else if(timeMath==timeNewton){
			System.out.print("The winner is ................ none.This is a draw.\n");
		}
		else{
			System.out.print("The winner is Newton.\n");
		}
	}
}

PS:sorry if some things are a little sloppy,I'm trying several things to debug this.