程序将两个矩阵相乘 · GeeksForGeeks 中文系列教程

# 程序将两个矩阵相乘 > 原文： [https://www.geeksforgeeks.org/c-program-multiply-two-matrices/](https://www.geeksforgeeks.org/c-program-multiply-two-matrices/) 给定两个矩阵，将它们相乘的任务。矩阵可以是正方形或矩形。 **示例**： ``` Input : mat1[][] = {{1, 2}, {3, 4}} mat2[][] = {{1, 1}, {1, 1}} Output : {{3, 3}, {7, 7}} Input : mat1[][] = {{2, 4}, {3, 4}} mat2[][] = {{1, 2}, {1, 3}} Output : {{6, 16}, {7, 18}} ``` ![](https://img.kancloud.cn/f1/1f/f11f23635de54933abc3f985cab0897b_461x340.png) **平方矩阵的乘积**：下面的程序将两个大小为 4 * 4 的平方矩阵相乘，我们可以为不同的维数更改 N。 ## C++ ```cpp // C++ program to multiply // two square matrices. #include <iostream> using namespace std; #define N 4 // This function multiplies // mat1[][] and mat2[][], and // stores the result in res[][] 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]; } } } // Driver Code int main() { int i, j; int res[N][N]; // To store result int mat1[N][N] = {{1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; int mat2[N][N] = {{1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; multiply(mat1, mat2, res); cout << "Result matrix is \n"; for (i = 0; i < N; i++) { for (j = 0; j < N; j++) cout << res[i][j] << " "; cout << "\n"; } return 0; } // This code is contributed // by Soumik Mondal ``` ## C ``` // C program to multiply two square matrices. #include <stdio.h> #define N 4 // This function multiplies mat1[][] and mat2[][], // and stores the result in res[][] 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 mat1[N][N] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; int mat2[N][N] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; int res[N][N]; // To store result int i, j; multiply(mat1, mat2, res); printf("Result matrix is \n"); for (i = 0; i < N; i++) { for (j = 0; j < N; j++) printf("%d ", res[i][j]); printf("\n"); } return 0; } ``` ## Java ```java // Java program to multiply two square // matrices. import java.io.*; class GFG { static int N = 4; // This function multiplies mat1[][] // and mat2[][], and stores the result // in res[][] static void multiply(int mat1[][], int mat2[][], int res[][]) { 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]; } } } // Driver code public static void main (String[] args) { int mat1[][] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; int mat2[][] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; // To store result int res[][] = new int[N][N] ; int i, j; multiply(mat1, mat2, res); System.out.println("Result matrix" + " is "); for (i = 0; i < N; i++) { for (j = 0; j < N; j++) System.out.print( res[i][j] + " "); System.out.println(); } } } // This code is contributed by anuj_67\. ``` ## Python 3 ``` # 4x4 matrix multiplication using Python3 # Function definition def matrix_multiplication(M,N): # List to store matrix multiplication result R = [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]] for i in range(0, 4): for j in range(0, 4): for k in range(0, 4): R[i][j] += M[i][k] * N[k][j] for i in range(0,4): for j in range(0,4): #if we use print(), by default cursor moves to next line each time, #Now we can explicitly define ending character or sequence passing #second parameter as end="<character or string>" #syntax: print(<variable or value to print>, end="<ending with>") #Here space (" ") is used to print a gape after printing #each element of R print(R[i][j],end=" ") print("\n",end="") # First matrix. M is a list M = [[1, 1, 1, 1], [2, 2, 2, 2], [3, 3, 3, 3], [4, 4, 4, 4]] # Second matrix. N is a list N = [[1, 1, 1, 1], [2, 2, 2, 2], [3, 3, 3, 3], [4, 4, 4, 4]] # Call matrix_multiplication function matrix_multiplication(M,N) # This code is contributed by Santanu ``` ## C# ```cs // C# program to multiply two square // matrices. using System; class GFG { static int N = 4; // This function multiplies mat1[][] // and mat2[][], and stores the result // in res[][] static void multiply(int[,] mat1, int [,]mat2, int [,]res) { 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]; } } } // Driver code public static void Main () { int [,]mat1 = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; int [,]mat2 = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4}}; // To store result int [,]res = new int[N,N] ; int i, j; multiply(mat1, mat2, res); Console.WriteLine("Result matrix" + " is "); for (i = 0; i < N; i++) { for (j = 0; j < N; j++) Console.Write( res[i,j] + " "); Console.WriteLine(); } } } // This code is contributed by anuj_67\. ``` ## PHP ```php <?php // PHP program to multiply two // square matrices. // This function multiplies mat1[][] and // mat2[][], and stores the result in res[][] function multiply(&$mat1, &$mat2, &$res) { $N = 4; for ($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]; } } } // Driver Code $mat1 = array(array(1, 1, 1, 1), array(2, 2, 2, 2), array(3, 3, 3, 3), array(4, 4, 4, 4)); $mat2 = array(array(1, 1, 1, 1), array(2, 2, 2, 2), array(3, 3, 3, 3), array(4, 4, 4, 4)); multiply($mat1, $mat2, $res); $N = 4; echo ("Result matrix is \n"); for ($i = 0; $i < $N; $i++) { for ($j = 0; $j < $N; $j++) { echo ($res[$i][$j]); echo(" "); } echo ("\n"); } // This code is contributed // by Shivi_Aggarwal ?> ``` **输出**： ``` Result matrix is 10 10 10 10 20 20 20 20 30 30 30 30 40 40 40 40 ``` **矩形矩阵的乘法**：我们在 C 中使用指针来乘法到矩阵。请参考以下帖子作为代码的前提条件。 [如何在 C 中将 2D 数组作为参数传递？](https://www.geeksforgeeks.org/pass-2d-array-parameter-c/) ## C++ ``` // C++ program to multiply two // rectangular matrices #include<bits/stdc++.h> using namespace std; // Multiplies two matrices mat1[][] // and mat2[][] and prints result. // (m1) x (m2) and (n1) x (n2) are // dimensions of given matrices. void multiply(int m1, int m2, int mat1[][2], int n1, int n2, int mat2[][2]) { int x, i, j; int res[m1][n2]; for (i = 0; i < m1; i++) { for (j = 0; j < n2; j++) { res[i][j] = 0; for (x = 0; x < m2; x++) { *(*(res + i) + j) += *(*(mat1 + i) + x) * *(*(mat2 + x) + j); } } } for (i = 0; i < m1; i++) { for (j = 0; j < n2; j++) { cout << *(*(res + i) + j) << " "; } cout << "\n"; } } // Driver code int main() { int mat1[][2] = { { 2, 4 }, { 3, 4 } }; int mat2[][2] = { { 1, 2 }, { 1, 3 } }; int m1 = 2, m2 = 2, n1 = 2, n2 = 2; multiply(m1, m2, mat1, n1, n2, mat2); return 0; } // This code is contributed // by Akanksha Rai(Abby_akku) ```