/* From: "A SURVEY OF COMPUTATIONAL PHYSICS" 
   by RH Landau, MJ Paez, and CC BORDEIANU 
   Copyright Princeton University Press, Princeton, 2008.
   Electronic Materials copyright: R Landau, Oregon State Univ, 2008;
   MJ Paez, Univ Antioquia, 2008; and CC BORDEIANU, Univ Bucharest, 2008.
   Support by National Science Foundation                              
   */
// Walk.java Random walk simulation	 
import java.io.*;															             // Location of PrintWriter
import java.util.*;															  	            // Location of Random
import java.lang.*;																	              // Location of Math

public class Walk {

	public static void main(String[] argv) throws IOException, FileNotFoundException { 
		PrintWriter q = new PrintWriter( new FileOutputStream("Walk.dat"), true); 
		int jmax = 100, i;
		double x, y;			
		x = 0. ;
		y = 0. ;                                                       // Start at origin
		for ( i=0;	i <= jmax;	i++ ) {
	      q.println("	" + x + "	" + y);                                 // Print points
	      x += (Math.random()-0.5)*2.;                             // Random -1=<x =< 1
		    y += (Math.random()-0.5)*2.;                             // Random -1=<y =< 1
		} 
        q.println("	" + x + "	" + y); 
		System.out.println(" "); 
		System.out.println("Walk Program Complete."); 
		System.out.println("Data stored in Walk.dat"); 
    System.out.println("Distance from origin "+ Math.sqrt(x*x+y*y));	
	} 
}