MPI学习二

1.规约

int MPI_Reduce(void * input_data_p, void * output_data_p, int count, MPI_Datatype datatype, MPI_Op operator, int dest_process, MPI_Comm comm)

 1 #include <stdio.h>
 2 #include <mpi.h>
 3 
 4 int main(int argc, char **argv)
 5 {
 6     int myid, numprocs;
 7     double local_num = 3.0; 
 8 
 9     MPI_Init(&argc, &argv);
10     
11     MPI_Comm_rank(MPI_COMM_WORLD, &myid);
12     MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
13     
14     double global_num;
15     
16     //your code here
17     MPI_Reduce(&local_num, &global_num, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
18     //end of your code
19     
20     if(myid == 0) {
21         printf("Total sum = %f, avg = %f
", global_num, global_num / numprocs);
22     }
23 
24     MPI_Finalize();
25     return 0;
26 }

2.广播

int MPI_Bcast(void* buffer, int count, MPI_Datatype datatype, int source, MPI_Comm comm)

 1 #include<stdio.h>
 2 #include<mpi.h>
 3 
 4 int main(int argc, char **argv)
 5 {
 6     int myid, numprocs;
 7     int source = 0;
 8     int array[5]={1,2,3,4,5};
 9     int i;
10     
11     MPI_Init(&argc, &argv);
12     
13     MPI_Comm_rank(MPI_COMM_WORLD, &myid);
14     MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
15     
16     if(myid == source) {
17         for(i = 1; i <= 5; i++)
18             array[i] = i;
19     }
20     
21     //your code here
22     MPI_Bcast(array, 5, MPI_INT, source, MPI_COMM_WORLD);
23     //end of your code
24     
25     if(myid != source) {
26         printf("In process %d, ", myid);
27         for(i = 0; i < 5; i++)
28             printf("arr[%d]=%d	", i, array[i]);
29         printf("
");
30     }
31 
32     MPI_Finalize();
33     return 0;
34 }

来自：MPI编程实训学习（超算习堂）