blackred1.c

在linux系统下

#include"mpi.h"
#include<stdio.h>
#include<math.h>
#include"time.h"

#define NODE 500000

#define CPU 5 
#define K 100000
#define TEM 10000.0
#define CONV  0.1
#define domain NODE/CPU    /* numbers of nodes in each domain*/



int i,j,k;


int main(int argc,char * argv[])
{
double u_curr[domain+2]={0.0},u_next[domain+2]={0.0};
double send_messfirst;
double send_messlast;
double recv_messfirst;
double recv_messlast;
double endtime,starttime;
int allrestart;
double conv;
int restart;
int begin_col,end_col;
int myid,procs;	
MPI_Status status;
double w;

/*init the variable*/


					   	
MPI_Init(& argc, & argv);
MPI_Comm_rank(MPI_COMM_WORLD, & myid);
MPI_Comm_size(MPI_COMM_WORLD, & procs);

begin_col=1;
end_col=domain;

if(myid==0)
{	
       u_curr[1]=0.0;
       u_next[1]=0.0;
	begin_col=2;
}	

if(myid==CPU-1)
{
       u_curr[domain]=TEM;
	u_next[domain]=TEM;
	end_col=domain-1;
}
	
starttime=MPI_Wtime();
	for(k=0; k<K; k++)
{
       
	 restart=0;

             //     #pragma omp for
	        for(i=begin_col; i<=end_col; i++)
			
			{
			         if(i%2!=0)
			            {
                                      u_next[i]=0.5*(u_curr[i-1]+u_curr[i+1]);
					 
                                      conv=u_next[i]-u_curr[i];
	                               if(fabs(conv)>CONV)
	                                                      restart=1;
	                           }
		         }
        
        
       if(myid!=0)
		      send_messfirst=u_next[1];
       if(myid<CPU-1)
			send_messlast=u_next[domain];

       if(myid!=0)
	         MPI_Send(&send_messfirst,1,MPI_DOUBLE,myid-1,0,MPI_COMM_WORLD);
       if(myid<CPU-1)
		  MPI_Send(&send_messlast,1,MPI_DOUBLE,myid+1,99,MPI_COMM_WORLD);  

	
       if(myid!=0)
	         MPI_Recv(&recv_messlast,1,MPI_DOUBLE,myid-1,99,MPI_COMM_WORLD,&status);
       if(myid<CPU-1)
		  MPI_Recv(&recv_messfirst,1,MPI_DOUBLE,myid+1,0,MPI_COMM_WORLD,&status);   


if(myid!=0)
   		u_next[0]=recv_messlast;
  
 if(myid<CPU-1)	
		u_next[domain+1]=recv_messfirst;	

		for(i=begin_col; i<=end_col; i++)
	
			{	if(i%2==0)
			      {
	                           u_next[i]=0.5*(u_next[i-1]+u_next[i+1]);
	                           conv=u_next[i]-u_curr[i];
	                           if(fabs(conv)>CONV)
	                                                 restart=1;

                            }
			}

	
			allrestart=0;
               
			MPI_Reduce(&restart,&allrestart,1,MPI_INT,MPI_SUM,0,MPI_COMM_WORLD);	
                     MPI_Bcast(&allrestart,1,MPI_INT,0,MPI_COMM_WORLD);
		   
			if(allrestart==0)
			{
			
				
				  endtime=MPI_Wtime(); 
		                printf("\n====================k is over!!!!   k==%d=============\n",k);   
				  printf("\n====================time == %.6f===================\n",endtime-starttime);
		               
			
				break;

			}

//#pragma omp for		   
	for(i=begin_col; i<=end_col; i++)
	{
	
		  u_curr[i]=u_next[i]; 
       }

       if(myid!=0)
		    send_messfirst=u_next[1];
                     if(myid<CPU-1)
			send_messlast=u_next[domain];

       if(myid!=0)
	         MPI_Send(&send_messfirst,1,MPI_DOUBLE,myid-1,0,MPI_COMM_WORLD);
       if(myid<CPU-1)
		  MPI_Send(&send_messlast,1,MPI_DOUBLE,myid+1,99,MPI_COMM_WORLD);  

	
       if(myid!=0)
	         MPI_Recv(&recv_messlast,1,MPI_DOUBLE,myid-1,99,MPI_COMM_WORLD,&status);
       if(myid<CPU-1)
		  MPI_Recv(&recv_messfirst,1,MPI_DOUBLE,myid+1,0,MPI_COMM_WORLD,&status);   


if(myid!=0)
   		u_curr[0]=recv_messlast;
  
 if(myid<CPU-1)	
		u_curr[domain+1]=recv_messfirst;	
}

		

	  printf("\n======================the points are:==========================\n");	
	  if(myid==CPU-1)
	  	for(i=domain-100; i<=domain; i++)
		{
		
		printf("  %.2f        ",u_next[i]);
		printf("\n");
      
   
	} 
	   printf("\n=================the   end======================================\n");
MPI_Finalize();
}