Final Project start

FinalProject/main.cpp

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+#include <iostream>
+#include <mpi.h>
+#include <stdlib.h>
+#include <time.h>
+#define MCW MPI_COMM_WORLD
+using namespace std;
+
+//Problem size
+const int N = 10;
+
+//global variables
+double A[N][N];
+double B[N][N];
+double AB[N][N];
+double AB_serial[N][N];
+
+//timing variables
+double time1,time2,time3;
+
+//Function to fill matrices at random
+void fill_matrices(){
+  srand(time(NULL));
+
+    for(int i = 0; i <N; i++){
+      for (int j = 0; j < N; j++){
+	A[i][j] = rand() %4;
+	B[i][j] = rand() %4;
+      }
+    }
+}
+
+//Function to print matrix
+void print_matrix(double mat[][N]){
+  for (int i = 0; i < N; i++){
+    for (int j = 0; j<N; j++){
+      cout << mat[i][j] << " ";
+    }
+    cout << endl;
+  }
+  cout << endl;
+}
+
+//Serial version of solution
+void serial_version(){
+  for (int i = 0; i <N; i++){
+    for (int j = 0; j < N;j++){
+      AB_serial[i][j] = 0;
+      for (int k = 0; k <N; k++){
+	AB_serial[i][j] += A[i][k]*B[k][j];
+      }
+    }
+  }
+}
+
+//Compute interval multiplication
+void compute_interval(int start,int interval){
+  for(int i = start; i <start+interval;i++){
+    for (int j = 0; j <N; j++){
+      AB[i][j] = 0;
+      for (int k = 0; k <N; k++){
+	AB[i][j] += A[i][k]*B[k][j];
+      }
+    }
+  }
+}
+
+int main(int argc, char** argv){
+  int interval, remainder, rank, size;
+  MPI_Init(&argc, &argv);
+  MPI_Comm_rank(MCW, &rank);
+  MPI_Comm_size(MCW, &size);
+
+  //compute interval size
+  //rank 0 responsible for remainder
+  interval = N/size;
+  remainder = N%size;
+
+  //Record start time
+  MPI_Barrier(MCW);
+  time1 = MPI_Wtime();
+
+  //Rank 0 fills the matrices and computes the remainder
+  if(!rank){
+    fill_matrices();
+    compute_interval(size*interval,remainder);
+  }
+
+  //Broadcast Matrix B and scatter relevant portions of Matrix A
+  MPI_Bcast(B,N*N,MPI_DOUBLE,0,MCW);
+  MPI_Scatter(A,interval*N,MPI_DOUBLE,A[rank*interval],interval*N,MPI_DOUBLE,0,MCW);
+
+  //Each processor cumputes the interval they are responsible for
+  compute_interval(rank*interval,interval);
+
+  //Gather results
+  MPI_Gather(AB[rank*interval],interval*N,MPI_DOUBLE,AB,interval*N,MPI_DOUBLE,0,MCW);
+
+  //Record parallel finish time
+  MPI_Barrier(MCW);
+
+  time2 = MPI_Wtime();
+
+  if (!rank){
+
+    //serial computation
+    serial_version();
+
+    //Record serial finish time
+    time3 = MPI_Wtime();
+
+    //Print times
+    cout << "Problem size " << N << endl;
+    cout << size << " processors computed in time: " << time2-time1 << endl;
+    cout << "Serial version computed in time: " << time3-time2 << endl;
+    cout << "Efficiency of: " << (time3-time2)/((time2-time1)*size) << endl;
+
+    //Code to print matrices and results
+
+    cout << "Matrix A: " << endl;
+    print_matrix(A);
+    cout << "multiplied Matrix B:" << endl;
+    print_matrix(B);
+    cout << "gives matrix AB:" << endl;
+    print_matrix(AB);
+    cout << "serial version gives:" << endl;
+    print_matrix(AB_serial);
+  }
+
+  MPI_Finalize();
+}