problem in matrix multiplication

Replies

• 

  pradeep_agrawal

  sahana

  i have to multiply 2 n*m matrices using pointers

  When you say pointers, do you meant that the matrices are implemented using linked list? Could you please provide more details on how the matrices are implemented.
  
  -Pradeep
• 

  sahana

  yeah u can implement it by a linked list.
• 

  friendster7

  if u need to multiply then check out this..this might help
  
  

   #include
  #include
  
  main()
  {
      int mtrx1[5][5],mtrx2[5][5],product[5][5],ro1,ro2,col1,col2;
      unsigned short int posblty;
      static unsigned short int call_main = 0;
      if(call_main == 0 || call_main % 10 == 0)
      {
          clrscr();
          printf("\nThis program will calculate the product of two matrices");
          printf("\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
      }
      call_main++;
      getnum(&ro1,1);
      getnum(&col1,3);
      getnum(&ro2,2);
      getnum(&col2,4);
      posblty = is_posble(col1,ro2);
      if(!posblty)
      {
          getch();
          repeat();
      }
      getmatrix(mtrx1,ro1,col1,1);
      getmatrix(mtrx2,ro2,col2,2);
      multiply(mtrx1,mtrx2,product,ro1,col2,col1);
      print_matrix(product,ro1,col2);
      find_trace(product,ro1,col2);
      repeat();
  }
  
  getnum(num,message)
  int *num,message;
  {
      do
      {
      switch(message)
      {
          case 1:
          printf("\nEnter the number of rows in matrix 1:");
          break;
  
          case 2:
          printf("\nEnter the number of rows in matrix 2:");
          break;
  
          case 3:
          printf("\nEnter the number of columns in matrix 1:");
          break;
  
          case 4:
          printf("\nEnter the number of columns in matrix 2:");
          break;
  
          default:
          printf("\nEnter a number:");
      }
      scanf("%d",num);
      }
      while(*num > 5);
      return;
  }
  
  is_posble(col_1,row_2)
  int row_2,col_1;
  {
      if(col_1 != row_2)
      {
          printf("\nThe multiplication of given matrices is not possible");
          return(0);
      }
      else
      {
          return(1);
      }
  }
  
  getmatrix(array,row,column,mtrx_num)
  int *array[5],row,column,mtrx_num;
  {
      int i,j;
      printf("\nEnter matrix %d\n",mtrx_num);
  
      for(i = 0;i < row;i++)
      {
          for(j = 0;j < column;j++)
          {
              scanf("%d",array+(5*i+j));
          }
      }
      return;
  }
  
  multiply(matrix1,matrix2,product,l,m,n)
  int *matrix1[5],*matrix2[5],*product[5],l,m,n;
  {
      int i,j,k,temp1,temp2,temp3;
  
      for(i=0;i < l;i++)
      {
          for(j = 0;j < m;j++)
          {
              *(product+(5*i+j)) = 0;
              for(k = 0;k < n;k++)
              {
                  temp1 = *(matrix1+(5*i+k));
                  temp2 = *(matrix2+(5*k+j));
                  temp3 = *(product+(5*i+j));
                  *(product+(5*i+j)) = temp1 * temp2 + temp3;
              }
          }
      }
      return;
  }
  
  print_matrix(array,row,col)
  int *array[5];
  {
      int i,j;
      printf("\nThe product is :");
      for(i = 0;i < row;i++)
      {
          printf("\n");
          for(j = 0;j < col;j++)
          {
              printf("%5d \t",*(array+(5*i+j)));
          }
      }
      return;
  }
  
  

• 

  sahana

  hi friendster7,
  i got your code.but is the most optimal?this code is designed for matrices which have a maximum of 5 rows and 5 columns right?so if i dont use a 5*5 matrix (say 3*3 ), its going to be a waste of space right?can we make it a little more optimal.how about dyanamic memory allocation?
  please tell me if i have undserstood it wrongly.
  another constraint i forgot to add in the question is that we cannot get the size of the matrix during runtime and then assign the subscript of the array.
  ie something like
  scanf("%d,%d",&rows,&col);
  int array[row][col];
  
  otherwise your code was really good.