package microbenchmarkmpiJava.gather;//// mpiJava version : Taboada//                   July 2002// DES//import java.io.*;import java.text.NumberFormat;import java.lang.Math;import mpi.*;public class Gather {  public static void main(String[] args) throws MPIException {  }  public Gather() {  }  public Gather(String[] args) throws Exception {    double      startwtime, endwtime, pot2npesd;    int         i, iterations, size, ns, my_pe, npes, localsize, pot2npes, pot2size;    Status      status;    MPI.Init(args);    my_pe = MPI.COMM_WORLD.Rank();    npes  = MPI.COMM_WORLD.Size();    MPI.COMM_WORLD.Barrier();		  iterations = Integer.parseInt(System.getProperty("ITERATIONS"));		  size = Integer.parseInt(System.getProperty("SIZE"));  	  localsize = size / npes;		        byte A[] = new byte [localsize];      byte B[] = new byte [size];	  	  double timesBcast[] = new double [iterations];	  	  double timesBcastReduce[] = new double [iterations];	        	for (i = 0; i < localsize; i++) {		A[i] = (byte)'0'; 	}      		pot2npes = (int)(Math.log(npes)/0.69314718);		pot2npesd = (double)(Math.log(npes)/0.69314718);				pot2size = (int)(Math.log(size)/1.386294361);		if (pot2size < 0) pot2size = 0;	         	    for (ns = 0; ns < iterations; ns++) {			    	  MPI.COMM_WORLD.Barrier();				  	  			  startwtime = MPI.Wtime();								        		  MPI.COMM_WORLD.Gather(A,0,localsize,MPI.BYTE,B,0,localsize,MPI.BYTE,0);//last one is the root				  		  			  endwtime = MPI.Wtime();		  	  timesBcast[ns] = (double) (1000000*(endwtime - startwtime));			  			  			}   				MPI.COMM_WORLD.Reduce(timesBcast, 0, timesBcastReduce, 0, iterations, MPI.DOUBLE, MPI.MAX, 0);		if (my_pe == 0) {			  //Format the Number to Display			  NumberFormat nf = NumberFormat.getInstance();              nf.setMaximumFractionDigits(6);              nf.setMinimumFractionDigits(6);				  		      for (i = 0; i < iterations; i++) {			  		System.out.print(nf.format((double) timesBcastReduce[i]/1000000)+" \t "+(long) timesBcastReduce[i]+" \t "+nf.format((double)(size/(timesBcastReduce[i]))));  			  		System.out.println(" \t "+npes+" \t "+pot2npes+" \t "+nf.format(pot2npesd)+" \t "+size+" \t "+pot2size);     		  			  }				}		    MPI.Finalize();       if(my_pe == 0)      System.out.println("Gather TEST COMPLETE");	     }}