MatrixMultiply.cpp

#include <cmath>
#include <iostream>
#include <vector>
#include <random>
#include <chrono>

#include "parallel.h"

void fillMatrix(std::vector<std::vector<double>> &matrix) {
  std::size_t length = matrix.size();
  std::mt19937 generator;
  std::uniform_real_distribution<double> distribution(0.0, 1.0);
  for (std::size_t i = 0; i < length; ++i) {
    for (std::size_t j = 0; j < length; ++j) {
      matrix[i][j] = distribution(generator);
    }
  }
}

int main() {
  std::cout << "Parallel Framework: " << PARALLEL_FRAMEWORK << std::endl;

  std::size_t length(1000);
  std::vector<std::vector<double>> a(length, std::vector<double>(length)),
      b(length, std::vector<double>(length)),
      c(length, std::vector<double>(length));
  fillMatrix(a);
  fillMatrix(b);

  std::chrono::high_resolution_clock::time_point t1 =
      std::chrono::high_resolution_clock::now();
  parallel_for_each(par, 0, length, [&a, &b, &c, length](std::size_t i) {
    for (std::size_t j = 0; j < length; ++j) {
      for (std::size_t k = 0; k < length; ++k) {
        c[i][j] += a[i][k] * b[k][j];
      }
    }
  });

  std::chrono::high_resolution_clock::time_point t2 =
      std::chrono::high_resolution_clock::now();
  std::chrono::duration<double> time_span =
      std::chrono::duration_cast<std::chrono::duration<double>>(t2 - t1);
  std::cout << "It took me " << time_span.count() << " seconds." << std::endl;

  std::cout << "serial fallback: " << std::endl;
  t1 = std::chrono::high_resolution_clock::now();
  parallel_for_each(seq, 0, length, [&a, &b, &c, length](std::size_t i) {
    for (std::size_t j = 0; j < length; ++j) {
      for (std::size_t k = 0; k < length; ++k) {
        c[i][j] += a[i][k] * b[k][j];
      }
    }
  });

  t2 = std::chrono::high_resolution_clock::now();
  time_span =
      std::chrono::duration_cast<std::chrono::duration<double>>(t2 - t1);
  std::cout << "It took me " << time_span.count() << " seconds." << std::endl;

  std::cout << "serial old: " << std::endl;
  t1 = std::chrono::high_resolution_clock::now();
  for (std::size_t i = 0; i < length; ++i) {
    for (std::size_t j = 0; j < length; ++j) {
      for (std::size_t k = 0; k < length; ++k) {
        c[i][j] += a[i][k] * b[k][j];
      }
    }
  }
  t2 = std::chrono::high_resolution_clock::now();
  time_span =
      std::chrono::duration_cast<std::chrono::duration<double>>(t2 - t1);
  std::cout << "It took me " << time_span.count() << " seconds." << std::endl;

  return 0;
}