programming-examples/c++/Others/Matrix Multiplication.cpp

Matrix Multiplication

void main()
{
	int row1=0,
	    col1=1,	
	    row2=0,
	    col2=0,
	    **matrix1,
	    **matrix2,
	    **result;

          clrscr();
          printf(" Enter number of row for first matrix ");
          scanf("%d",&row1);
   
          while (col1!=row2)
   	    {	
	          printf(" Enter number of column for first matrix ");
	          scanf("%d",&col1);

	          printf(" Enter number of row for second matrix ");
	          scanf("%d",&row2);
		
	         if (col1!=row2)	
	         {
                   clrscr();
				   printf("Column number of first matrix must be same as the row number of second matrix");	    
	         }
		
		
	   }


          printf(" Enter number of column for second matrix ");
          scanf("%d",&col2);
         
          matrix1=init(matrix1,row1,col1);
          matrix2=init(matrix2,row2,col2);
         /* setting values in matrix */
		  printf("First matrix \n");
          set(matrix1,row1,col1);
		  printf("Second matrix \n");
          set(matrix2,row2,col2);
          /* printint matrix */
          clrscr();
          printf("       [ First matrix ]\n");		
          get(matrix1,row1,col1);
          printf("       [ Second matrix ]\n");		 	
          get(matrix2,row2,col2);		

		  printf("       [ Multiplication Result ]\n");
          result=mul(matrix1,matrix2,row1,col2,col1);
          get(result,row1,col2);	
		  printf("\n\t\t Thanks  from debmalya jash");
          getch();
          free(matrix1);
	  free(matrix2);
	  fress(result); 	
         
	
} /* end main */


/* to initialize matrix */
int** init(int** arr,int row,int col)
{
               int i=0,
                   j=0;

	arr=(int**)malloc(sizeof(int)*row*col);

	for(i=0;i<row;i++)
	{
		for(j=0;j<col;j++)
		{
			*((arr+i)+j)=(int*)malloc(sizeof(int));
            *(*(arr+i)+j)=0; 
		}
	}
	return arr;
}

/* to set value in matrix */
int** set(int** arr,int row,int col)
{
	int i=0,
        j=0,
	    val=0;
               
            for(i=0;i<row;i++)
	{
		for(j=0;j<col;j++)
		{
			printf("Enter value for row %d col %d  :",(i+1),(j+1));
			scanf("%d",&val);
			*(*(arr+i)+j)=val;
		}
	}
	return arr;
}


/* print values of the passed matrix */
void get(int** arr,int row,int col)
{
	int i=0,
	    j=0;

	for(i=0;i<row;i++)
	{
		for(j=0;j<col;j++)
		{
			printf("%d\t",*(*(arr+i)+j));
		}
		printf("\n");
	}	
}

/* mutiply two matrices and return the resultant matrix */
int** mul(int** arr1,int** arr2,int row,int col,int col1)
{
	int  **result,
	         i=0,
	         j=0,
	         k=0;

	result=init(result,row,col);
	
	for(i=0;i<row;i++)
	{
		for(j=0;j<col;j++)
		{
			for(k=0;k<col1;k++)
			{
				printf("%dX%d(%d)",*(*(arr1+i)+k),*(*(arr2+k)+j),(*(*(arr1+i)+k))*(*(*(arr2+k)+j))); 
				*(*(result+i)+j)+=(*(*(arr1+i)+k))*(*(*(arr2+k)+j));
				
				if (k!=(col1-1))
					printf("+");
			}
			printf("\t");
		}
		printf("\n");	
	}
	return result;