code

#include "pch.h"
#include <iostream>
#include <omp.h>

#define n 1000
using namespace std;
double par, seq;
bool show_c = 0;
float A[n][n] = { 0 };
float B[n] = { 0 };
float C0[n] = { 0 };
float C1[n] = { 0 };
float C2[n] = { 0 };
float C4[n] = { 0 };

void print_vector(float arr[n]) {
    for (int i = 0; i < n; i++) {
        printf("%.2f ", arr[i]);
    }
    cout << "\n";
}

void parallel_method(float A[n][n], float B[n], float C[n], int thr_num)
{
    double t1, t2;
    float tmp = 0;
    int i, j;

    t1 = omp_get_wtime();
    omp_set_dynamic(0);
    omp_set_num_threads(thr_num);
#pragma omp parallel private(tmp, j)
    {
#pragma omp for
        for (i = 0; i < n; i++) {
            tmp = 0;
            for (j = 0; j < n; j++) {
                tmp += A[i][j] * B[j];
            }
            C[i] += tmp;
        }
        t2 = omp_get_wtime();
    }
    if (show_c) print_vector(C);
    par = t2 - t1;
    printf("Parallel_method (%d c) time = %.15f\n", thr_num, par);
    //printf("Parallel Speedup = %.3f\n", seq / par);
    //printf("Parallel Efficiency = %.3f\n", seq / (par * thr_num));
}

void sequential_method(float A[n][n], float B[n], float C[n])
{
    double ts1, ts2;
    float tmp = 0;

    ts1 = omp_get_wtime();
    for (int i = 0; i < n; i++) {
        tmp = 0;
        for (int j = 0; j < n; j++) {
            tmp += A[i][j] * B[j];
        }
        C[i] = tmp;
    }

    ts2 = omp_get_wtime();

    if (show_c) print_vector(C);
    seq = ts2 - ts1;
    printf("seq_method time = %.15f\n", seq);
}

int main()
{
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            A[i][j] = (float)(i + 1) * log(j + 1);
        }
        B[i] = (float)sqrt(i + 1);
    }
    cout << "n = " << n << endl << endl;
    sequential_method(A, B, C0);
    parallel_method(A, B, C1, 1);
    parallel_method(A, B, C2, 2);
    parallel_method(A, B, C4, 4);

    return 0;
}