Thread: Pruduct of matrixes

http://mathworld.wolfram.com/MatrixMultiplication.html

Here is a quick although, not complete example...

Code:

/*================================================
 A program which performs matrix 
 multiplication.
 
 Notes
 -----
 Multiplication can only take place iff
 the number of columns in matrix A is equal 
 to the number of rows in matrix B.
 
 Or as I like to remember it:
     
       C A R B
       
 Columns in
 A must equal
 Rows in
 B
 
 ================================================*/

#include <iostream>

using namespace std;


//Function declarations
void mmult(int,int,int[][100],int[][100]);

int main()
{
    //Hard code matrix A
    int m1[100][100] = {{1,5},
                        {2,7},
                        {3,4}};
    
    //Hard code matrix B
    int m2[100][100] = {{8,4,3,1},
                        {2,5,8,6}};
    //call function
    mmult(3,4,m1,m2);
    
    //Where '3' is the maximum number of rows in either
    //matrix A or B
    //and '4' is the maximun number of columns in either
    //matrix A or B
    
    cin.get();
    cin.get();             
     
   return 0;
}    
/*=================================================  =====
  Function to multiply matrix
 ==================================================  ===*/                  
void mmult (int rows, int cols, int m1[][100], int m2[][100]) 
{
    int m3[100][100];//holds the result of A * B
    for (int i=0; i<rows; i++) 
    {
        for (int j=0; j<cols; j++) 
        {
          int val = 0;
          for (int k=0; k<cols; k++) 
          {
            val = val + m1[i][k] * m2[k][j];
          }
          m3[i][j] = val;
        }
    }
    //print matrix
    for (int i=0; i<rows; i++) 
    {
        for (int j=0; j<cols; j++) 
        {
          cout<<" "<<m3[i][j];

          
        }
        cout<<"\n";
    }
}