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#include <iostream>
#include "mpi.h"
#include <chrono>
#include <fstream>
#include <vector>
#include <sstream>
using namespace std;
int main(int argc, char* argv[]) {
? ? const int ROOT = 0;
? ? int rank, size, n_rows, n_cols;
? ? double start_time, end_time;
? ? MPI_Init(&argc, &argv);
? ? MPI_Comm_rank(MPI_COMM_WORLD, &rank);
? ? MPI_Comm_size(MPI_COMM_WORLD, &size);
? ? // get file name from command line argument
? ? string filename = argv[1];
? ? ifstream data_file;
? ? if (rank == ROOT) {
? ? ? ? data_file.open(filename);
? ? ? ? if (!data_file.is_open()) {
? ? ? ? ? ? cerr << "Failed to open file: " << filename << endl;
? ? ? ? ? ? exit(1);
? ? ? ? }
? ? ? ? // read number of rows and columns
? ? ? ? data_file >> n_rows >> n_cols;
? ? }
? ? // broadcast number of rows and columns to all processes
? ? MPI_Bcast(&n_rows, 1, MPI_INT, ROOT, MPI_COMM_WORLD);
? ? MPI_Bcast(&n_cols, 1, MPI_INT, ROOT, MPI_COMM_WORLD);
? ? // calculate number of rows for each process
? ? int rows_per_process = n_rows / size;
? ? int remainder = n_rows % size;
? ? if (rank < remainder) {
? ? ? ? rows_per_process++;
? ? }
? ? vector<double> row_values(n_cols, 0);
? ? // read data rows and calculate average for each row
? ? MPI_Barrier(MPI_COMM_WORLD);
? ? start_time = MPI_Wtime();
? ? for (int i = 0; i < rows_per_process; i++) {
? ? ? ? if (rank == ROOT) {
? ? ? ? ? ? // read row from file
? ? ? ? ? ? for (int j = 0; j < n_cols; j++) {
? ? ? ? ? ? ? ? data_file >> row_values[j];
? ? ? ? ? ? }
? ? ? ? }
? ? ? ? // broadcast row values to the other processes
? ? ? ? MPI_Bcast(row_values.data(), n_cols, MPI_DOUBLE, ROOT, MPI_COMM_WORLD);
? ? ? ? // calculate average for each row
? ? ? ? double sum = 0;
? ? ? ? for (int j = 0; j < n_cols; j++) {
? ? ? ? ? ? sum += row_values[j];
? ? ? ? }
? ? ? ? double avg = sum / n_cols;
? ? ? ? if (rank == ROOT) {
? ? ? ? ? ? cout << "Average of row " << i << ": " << avg << endl;
? ? ? ? }
? ? }
? ? MPI_Barrier(MPI_COMM_WORLD);
? ? end_time = MPI_Wtime();
? ? // get total time and output to console
? ? double total_time = end_time - start_time;
? ? if (rank == ROOT) {
? ? ? ? cout << "Total time: " << total_time << " seconds" << endl;
? ? }
? ? // close file and finalize MPI
? ? if (rank == ROOT) {
? ? ? ? data_file.close();
? ? }
? ? MPI_Finalize();
? ? return 0;
}
mpicxx -o average.exe average.cpp
mpirun -np <number of processes> ./average.exe <filename>
