【母函数】母函数前提知识：矩阵相乘

A=2*3
1 2 3
4 5 6

B=3*4
1 2 3 4
5 6 7 8
4 3 2 1

R = A*B

思路：A矩阵第一行乘Ｂ矩阵第一列得等Ｒ矩阵的第一行第一列的值，以此类推。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

import java.util.* ; public class MatrixMultiply { public static void main ( String args []){ Scanner sc = new Scanner ( System . in ); int m = sc . nextInt (); int n = sc . nextInt (); int o = sc . nextInt (); int p = sc . nextInt (); int [][] a = new int [ m ][ n ]; int [][] b = new int [ o ][ p ]; int [][] r = new int [ m ][ p ]; //输入矩阵a 2行3列 a[0]= 1 2 3 // a[1]= 4 5 6 for ( int i = 0 ; i < a . length ; i ++){ for ( int j = 0 ; j < a [ i ]. length ; j ++){ a [ i ][ j ]= sc . nextInt (); } } //输入矩阵b for ( int i = 0 ; i < b . length ; i ++){ for ( int j = 0 ; j < b [ i ]. length ; j ++){ b [ i ][ j ]= sc . nextInt (); } } //矩阵相乘 for ( int i = 0 ; i < a . length ; i ++){ //A矩阵按行走 for ( int j = 0 ; j < b [ i ]. length ; j ++){ //B矩阵按列走 //计算r[i][j] r [ i ][ j ]= 0 ; for ( int k = 0 ; k < b . length ; k ++){ r [ i ][ j ] = r [ i ][ j ]+ a [ i ][ k ]* b [ k ][ j ]; } } } Magic . print2 ( r );//这是一个输出函数，可以自己写 } }