first commit

example/parallellHello.cpp

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+#include <iostream>
+#include <mpi.h>
+
+#define MCW MPI_COMM_WORLD
+using namespace std;
+
+int main(int argc, char **argv){
+    int rank;
+    int size;
+    int data;
+
+    MPI_Init(&argc, &argv);
+
+    //returns my rank in the MCW.
+    MPI_Comm_rank(MCW, &rank);
+    //how many things there are in this communicator.
+    MPI_Comm_size(MCW, &size);
+
+    //Sends info
+        //&rank- location of send buffer.
+        //1- how many things in the buffer.
+        //MPI_INT- tells what type to turn the data into..
+        //(rank+1)%size- return number.
+        //0- tag
+        //MCW- communicator and other things.
+    MPI_Send(&rank, 1, MPI_INT, (rank+1)%size, 0, MCW);
+    
+    //Recieves information
+        //&data where to put the return data.
+        //1- how many.
+        //MPI_INT- type.
+        //MPI_ANY_SOURCE- can come from any process.
+        //0- tag.
+        //mcw- communicator type
+        //MPI_STATUS_IGNORE- 
+    MPI_Recv(&data, 1, MPI_INT, MPI_ANY_SOURCE, 0, MCW, MPI_STATUS_IGNORE);
+
+    cout << "I am " << rank << " of " << size << "; got a message from " << data <<endl;
+
+    MPI_Finalize();
+    return 0;
+}