.

hello_world.cpp

@@ -0,0 +1,40 @@
+#include <mpi.h>
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  // Initialize the MPI environment
+  MPI_Init(&argc, &argv);
+
+  // Get the number of processes
+  int world_size;
+  MPI_Comm_size(MPI_COMM_WORLD, &world_size);
+
+  // Get the rank of the process
+  int world_rank;
+  MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
+
+  // Get the name of the processor
+  char processor_name[MPI_MAX_PROCESSOR_NAME];
+  int name_len;
+  MPI_Get_processor_name(processor_name, &name_len);
+
+  // Print off a hello world message
+  printf("Hello world from %s, rank %d out of %d processors\n", processor_name,
+         world_rank, world_size);
+
+  int dst_rank = (world_rank + 1) % world_size;
+  int src_rank = world_rank - 1;
+  if (src_rank < 0) {
+    src_rank = world_size - 1;
+  }
+  float val = world_rank;
+  MPI_Send(&val, 1, MPI_FLOAT, dst_rank, 0, MPI_COMM_WORLD);
+  MPI_Status stat;
+  MPI_Recv(&val, 1, MPI_FLOAT, src_rank, 0, MPI_COMM_WORLD, &stat);
+
+  printf("rank %d got %f\n", world_rank, val);
+
+  // Finalize the MPI environment.
+  MPI_Finalize();
+  return 0;
+}