lab6_q2_ced17i031.c

#include <mpi.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 

// size of array 
#define n 400000000
int main(int argc, char* argv[]) 
{ 

double start;
double end;
double maximum_end = 0;
double minimum_start = 10000;
double sum;

int processid;
int np;
int elements_per_process;
int n_elements_recieved;
int SIZE; 

double productproduct;
MPI_Status status; 

MPI_Init(&argc, &argv); 
MPI_Comm_rank(MPI_COMM_WORLD, &processid); 
MPI_Comm_size(MPI_COMM_WORLD, &np);

elements_per_process = n / np; 
printf("\nthe element_per_process is %d\n",elements_per_process); 
int count = 0;

SIZE = elements_per_process*np;
MPI_Barrier(MPI_COMM_WORLD);

start = MPI_Wtime();

if (processid == 0) 
{

double product;
int location;
int i; 
double* a = (double*) malloc(SIZE*sizeof(double));
double* b = (double*) malloc(SIZE*sizeof(double));
double* sum = (double*) malloc(SIZE*sizeof(double));

for( i=0; i<n; i++)
	a[i] = (double) rand() + 0.00001534784187571354923459*(double) rand();//rand()%10;
for( i=0; i<n; i++)
	b[i] = (double) rand() + 0.00001534784187571354923459*(double) rand();//rand()%10;
product=0.0;
count=0;
int t;
t = (int) n%np;
if(np>1)
{
                printf("\nthe elements left %d\n",n%np);
			if(n%np != 0)
			{
			    	for(i=np*t;i<n;i++)
			    	{ 
					product+=a[i]*b[i];
			    	}
			}  
for ( i = 1; i < np; i++) 
{ 
				location = i * elements_per_process; 

				MPI_Send(&elements_per_process, 1, MPI_INT, i, 0,MPI_COMM_WORLD); 
				MPI_Send(&a[location],elements_per_process,MPI_DOUBLE, i, 1,MPI_COMM_WORLD);
                                MPI_Send(&b[location],elements_per_process, MPI_DOUBLE, i, 2,MPI_COMM_WORLD); 
} 
}
for (i = 0; i < elements_per_process; i++) 
	product+= a[i]*b[i]; 
printf("\nMaster rank finished\n");
 MPI_Reduce(&product, &productproduct, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD); 
int k;

}

else { 
double product1;
double* a2 = (double*) malloc(SIZE*sizeof(double));
double* b2 = (double*) malloc(SIZE*sizeof(double));
product1=0.0;

		MPI_Recv(&n_elements_recieved, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &status); 
		MPI_Recv(a2, n_elements_recieved, MPI_DOUBLE, 0, 1, MPI_COMM_WORLD, &status);
		MPI_Recv(b2, n_elements_recieved, MPI_DOUBLE, 0, 2, MPI_COMM_WORLD, &status); 
		int i; 
		for ( i = 0; i < n_elements_recieved; i++) 
			product1+= a2[i]*b2[i]; 
  MPI_Reduce(&product1, &productproduct, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD); 
                printf("\nDATA SENT-%d\n",processid);
	}
MPI_Barrier(MPI_COMM_WORLD);
end = MPI_Wtime();
MPI_Finalize(); 
   if(minimum_start > start){
        minimum_start = start;
    }
    if(maximum_end < end){
        maximum_end = end;
    }
    if(processid == 0){
        printf("\nExect time is %lf\n",end-start);
    }
	return 0; 
}