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  1. #include <mpi.h>
  2. #include <stdio.h>
  3.  
  4. int main(int argc, char *argv[]) {
  5.     int myrank, root = 0;
  6.     MPI_Comm comm = MPI_COMM_WORLD;
  7.  
  8.     // Initialize MPI environment
  9.     MPI_Init(&argc, &argv);
  10.     MPI_Comm_rank(comm, &myrank);
  11.  
  12.     // Define arrays for input and output
  13.     double ain[30], aout[30];
  14.     int ind[30];
  15.  
  16.     // Structure to hold value and rank
  17.     struct {
  18.         double val;
  19.         int rank;
  20.     } in[30], out[30];
  21.  
  22.     // Initialize input array
  23.     for (int i = 0; i < 30; ++i) {
  24.         ain[i] = (double)(myrank + i);  // Each process has its own set of values
  25.         in[i].val = ain[i];
  26.         in[i].rank = myrank;
  27.     }
  28.  
  29.     // Perform reduction to find the maximum value and corresponding rank (MPI_MAXLOC)
  30.     MPI_Reduce(in, out, 30, MPI_DOUBLE_INT, MPI_MAXLOC, root, comm);
  31.  
  32.     // Process root collects and prints the result
  33.     if (myrank == root) {
  34.         printf("Results from process %d:\n", root);
  35.         for (int i = 0; i < 30; ++i) {
  36.             aout[i] = out[i].val;
  37.             ind[i] = out[i].rank;
  38.             printf("Max value at index %d: %f from process %d\n", i, aout[i], ind[i]);
  39.         }
  40.     }
  41.  
  42.     // Finalize MPI environment
  43.     MPI_Finalize();
  44.     return 0;
  45. }
  46.  
Success #stdin #stdout #stderr 0.31s 40716KB
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Standard input is empty
stdout
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Standard output is empty
stderr
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Error: unexpected symbol in "int main"
Execution halted
https://ideone.com/X5venH
language:
R (R 3.5.2)
created:
3 days ago
visibility:
public

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