Java小程序--矩阵加法和矩阵乘法

版权声明： https://blog.csdn.net/qq_32715175/article/details/79701218

package testArray2;
/**
 * 练习矩阵,封装矩阵常用算法
 * @author Shinelon
 *
 */
public class Matrix {
 public static void print(int[][] c){
  for(int i = 0;i<c.length;i++){
   for(int j = 0;j<c.length;j++){
    System.out.print(c[i][j]+"\t");
   }
   System.out.println();
  }
  System.out.println();
 }
 
 //加法
 public static int[][] add(int[][] a,int[][] b){
  int[][] c = new int [a.length][b[0].length];
  for(int i = 0;i<a.length;i++){
   for(int j = 0;j<b[0].length;j++){
    c[i][j]=a[i][j]+b[i][j];
   }
  }
  return c;
 }
 
 //乘法
 public static int[][] multiply(int[][] a,int[][] b){
  if (a[0].length != b.length)  
            return null; 
  int[][] c = new int [a.length][b[0].length];
  for(int i = 0;i<a.length;i++){
   for(int j = 0;j<b[0].length;j++){
    for(int k = 0;k<b.length;k++){
     c[i][j] += a[i][k] * b[k][j];  //c[i][j]等于a[i]所在的行分别乘以b[j]所在的列对应值的和
    }
   }
  }
  return c;
 }
 
 public static void main(String[] args) {
  int[][] a = {
    {1,3,4},
    {2,4,6},
    {1,2,3}
  };
  int[][] b = {
    {3,4,2},
    {5,6,3},
    {2,2,4}
  };
  
  print(add(a, b));
  
  int[][] c = {
    {1,3},
    {2,4},
    {1,2}
  };
  int[][] d = {
    {3,4,2},
    {5,6,3}
  };
  
  print(multiply(c, d));
 }
}

结果为

4 7 6 
7 10 9 
3 4 7 

18 22 11 
26 32 16 
13 16 8