serial_br.c

在linux系统下G－S算法

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

#define NODE 500000


#define K 100000
#define TEM 10000.0
#define CONV  0.1
   



int i,j,k;


int main(int argc,char * argv[])
{
double u_curr[NODE]={0.0},u_next[NODE]={0.0};

double endtime,starttime;
int allrestart;
double conv;
int restart;
int begin_col,end_col;
int myid,procs;	
MPI_Status status;


/*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=NODE-1;



       u_curr[NODE-1]=TEM;
	u_next[NODE-1]=TEM;
	

starttime=MPI_Wtime();
	for(k=0; k<K; k++)
{
       
	 restart=0;

       
	        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;
	                           }
		         }
        
        
    
		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;

                            }
			}

	
			
			if(restart==0)
			{
			
				
				  endtime=MPI_Wtime(); 
		                printf("\n====================k is over!!!!   k==%d=============\n",k);   
				  printf("\n====================time == %.6f===================\n",endtime-starttime);
		               
			
				break;
			}
     else
	 	for(i=begin_col; i<end_col; i++)
	{
	
		  u_curr[i]=u_next[i]; 
       }

}

		

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