Question

Consider the product of two matrices A and B of dimensions 4 x 4 as shown below 100 00 I 1 01 23 I 1 0 2 46 X 0369 1 01 2 3 I | 1 2 3 4 234 5 I 1 3 45 6 I | 14 20 26 32 - 28 40 52 64I 1 42 60 78 96I 1. Write a program to find the product of two matrices. The program should display the two input matrices and the output product matrix. 2. Modify the program by using four threads to perform the matrix product concurrently. Decide on how to distribute the task over the four threads. Each thread will display each element of the product matrix immediately after it is calculated in order to observe the concurrency between the threads. The expected output of your program should look somehow similar to the sample display below Matrix A 0 2 4 6 Matrix B 0 1 2 3 1 2 3 4

Answer 1

Answer:

1)

#include <iostream>

using namespace std;

#define N 4

void multiply(int mat1[][N],

int mat2[][N],

int res[][N])

{

int i, j, k;

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

{

res[i][j] = 0;

for (k = 0; k < N; k++)

res[i][j] += mat1[i][k] *

mat2[k][j];

}

}

}

int main()

{

int i, j;

int res[N][N];

int mat1[N][N] = {{0, 0, 0, 0},

{0, 1, 2, 3},

{0, 2, 4, 6},

{0, 3, 6, 9}};

int mat2[N][N] = {{0, 1, 2, 3},

{1, 2, 3, 4},

{2, 3, 4, 5},

{3, 4, 5, 6}};

cout << "Matrix A is \n";

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

cout << mat1[i][j] << " ";

cout << "\n";

}

cout << "\nMatrix B is \n";

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

cout << mat2[i][j] << " ";

cout << "\n";

}

multiply(mat1, mat2, res);

cout << "\nResult matrix is \n";

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

cout << res[i][j] << " ";

cout << "\n";

}

return 0;

}

2)

#include <bits/stdc++.h>

using namespace std;

#define MAX 4

#define MAX_THREAD 4

int matA[MAX][MAX] = {{0, 0, 0, 0},

{0, 1, 2, 3},

{0, 2, 4, 6},

{0, 3, 6, 9}};

int matB[MAX][MAX] = {{0, 1, 2, 3},

{1, 2, 3, 4},

{2, 3, 4, 5},

{3, 4, 5, 6}};

int matC[MAX][MAX];

int step_i = 0;

void* multi(void* arg)

{

int core = step_i++;

for (int i = core * MAX / 4; i < (core + 1) * MAX / 4; i++)

for (int j = 0; j < MAX; j++)

for (int k = 0; k < MAX; k++)

matC[i][j] += matA[i][k] * matB[k][j];

}

int main()

{

int i, j;

  

cout << endl

<< "Matrix A" << endl;

for (int i = 0; i < MAX; i++) {

for (int j = 0; j < MAX; j++)

cout << matA[i][j] << " ";

cout << endl;

}

cout << endl

<< "Matrix B" << endl;

for (int i = 0; i < MAX; i++) {

for (int j = 0; j < MAX; j++)

cout << matB[i][j] << " ";

cout << endl;

}

pthread_t threads[MAX_THREAD];

for (int i = 0; i < MAX_THREAD; i++) {

int* p;

pthread_create(&threads[i], NULL, multi, (void*)(p));

}

for (int i = 0; i < MAX_THREAD; i++)

pthread_join(threads[i], NULL);

cout << endl

<< "Multiplication of A and B" << endl;

for (int i = 0; i < MAX; i++) {

for (int j = 0; j < MAX; j++)

cout << matC[i][j] << " ";

cout << endl;

}

return 0;

}