并行计算之向量的计算

谁践踏了优雅 2022-08-10 00:58 292阅读 0赞

#include <stdio.h>
    #include <stdlib.h>
    #include <mpi.h>
    
    void Read_n(int* n_p, int* local_n_p, int my_rank,
    int comm_sz, MPI_Comm comm);
    void Allocate_vectors(double** local_x_pp, 
      double** local_y_pp,
      double** local_z_pp, 
      int local_n, MPI_Comm comm);
    void Read_vector(double local_a[], int local_n, 
     int n, char vec_name[], 
     int my_rank, MPI_Comm comm);
    void Print_vector(double local_b[], int local_n,
      int n, char title[], 
      int my_rank, MPI_Comm comm);
    void Parallel_vector_sum(double local_x[], 
     double local_y[], 
     double local_z[], 
     int local_n);
    
    
    int main(void) {
       int n, local_n;
       int comm_sz, my_rank;
       double *local_x, *local_y, *local_z;
       MPI_Comm comm;
    
       MPI_Init(NULL, NULL);
       comm = MPI_COMM_WORLD;
       MPI_Comm_size(comm, &comm_sz);
       MPI_Comm_rank(comm, &my_rank);
    
       Read_n(&n, &local_n, my_rank, comm_sz, comm);
       printf("Proc %d > n = %d, local_n = %d\n", 
          my_rank, n, local_n);
    
       Allocate_vectors(&local_x, &local_y, 
                    &local_z, local_n, comm);
    
       Read_vector(local_x, local_n, n, "x", my_rank, comm);
       Print_vector(local_x, local_n, n, "x is", my_rank, comm);
       Read_vector(local_y, local_n, n, "y", my_rank, comm);
       Print_vector(local_y, local_n, n, "y is", my_rank, comm);
    
       Parallel_vector_sum(local_x, local_y, local_z, local_n);
       Print_vector(local_z, local_n, n, "The sum is", 
                my_rank, comm);
       
       free(local_x);
       free(local_y);
       free(local_z);
    
       MPI_Finalize();
    
       return 0;
    }
    
    void Read_n(int* n_p, int* local_n_p, int my_rank,
    int comm_sz, MPI_Comm comm) {
       if (my_rank == 0) {
          printf("What's the order of the vectors?\n");
          scanf("%d", n_p);
       }
       MPI_Bcast(n_p, 1, MPI_INT, 0, comm);
       *local_n_p = *n_p/comm_sz;
    }
    
    void Allocate_vectors(double** local_x_pp, 
      double** local_y_pp,
      double** local_z_pp, 
      int local_n, MPI_Comm comm) {
       *local_x_pp = (double *)malloc(local_n*sizeof(double));
       *local_y_pp = (double *)malloc(local_n*sizeof(double));
       *local_z_pp = (double *)malloc(local_n*sizeof(double));
    }
    
    void Read_vector(double local_a[], int local_n, 
     int n, char vec_name[], 
     int my_rank, MPI_Comm comm) {
       double* a = NULL;
       int i;
    
       if (my_rank == 0) {
          a = (double *)malloc(n*sizeof(double));
          printf("Enter the vector %s\n", vec_name);
          for (i = 0; i < n; i++)
             scanf("%lf", &a[i]);
          MPI_Scatter(a, local_n, MPI_DOUBLE, 
      local_a, local_n, MPI_DOUBLE, 0, comm);
          free(a);
       }
       else {
          MPI_Scatter(a, local_n, MPI_DOUBLE, 
      local_a, local_n, MPI_DOUBLE, 0, comm);   
       }
    }
    
    void Print_vector(double local_b[], int local_n,
      int n, char title[], 
      int my_rank, MPI_Comm comm) {
       double* b = NULL;
       int i;
    
       if (my_rank == 0) {
          b = (double *)malloc(n*sizeof(double));
          MPI_Gather(local_b, local_n, MPI_DOUBLE, b, 
      local_n, MPI_DOUBLE, 0, comm);
          printf("%s\n", title);
          for (i = 0; i < n; i++)
             printf("%f ", b[i]);
          printf("\n");
          free(b);
       } 
       else {
          MPI_Gather(local_b, local_n, MPI_DOUBLE, b, 
      local_n, MPI_DOUBLE, 0, comm);  
       }
    }
    
    void Parallel_vector_sum(double local_x[], 
     double local_y[], 
     double local_z[], 
     int local_n) {
       int local_i;
    
       for (local_i = 0; local_i < local_n; local_i++)
          local_z[local_i] = local_x[local_i] + local_y[local_i];
    
    }

VC6运行效果图

![20151107212833744][]

MPI运行效果图

![20151107212842332][]

[20151107212833744]: /images/20220731/35cb3b1b58e24865831c64e8397ef0c6.png
[20151107212842332]: /images/20220731/6294efd8ff8a4218ac778cb356881b72.png