1. Introduction to Programming
Lecture 44

2. Class Matrix class Matrix { private : int numRows , numCols ;
double ** elements ;
} ;

3. Class Matrix class Matrix { private : int numRows , numCols ;
double ** elements ;
public :
Matrix ( int = 0 , int = 0 ) ; // Default constructor
Matrix ( const Matrix & ) ; // Copy constructor
~ Matrix ( ) ; // Destructor

4. Class Matrix // Utility functions of Matrix class
int getRows ( void ) const ;
int getCols ( void ) const ;
// Input output functions for Matrix class
const Matrix & input ( istream & is = cin ) ;
const Matrix & input ( ifstream & is ) ;
void output ( ostream & os = cout ) const ;
void output ( ofstream & os ) const ;

5. Class Matrix // Plus Operator Matrix operator + ( Matrix & m ) const ;
Matrix operator + ( double d ) const ;

6. d is a variable of type double ‘A’ is an object of a class Matrix
A + d ;

7. d is a variable of type double ‘a’ is an object of a class Matrix
d + A ;

8. Class Matrix // Plus Operator Matrix operator + ( Matrix & m ) const ;
Matrix operator + ( double d ) const ;
friend Matrix operator + ( double d , Matrix & m ) ;
const Matrix & operator += ( Matrix & m ) ;

9. i += 3 ;
i = i + 3 ;
A += B ; // A and B are Matrices

10. Where A and B are both matrices
A – B
Where A and B are both matrices

11. d is a variable of type double ‘A’ is an object of a class Matrix
A – d ;

12. d is a variable of type double ‘a’ is an object of a class Matrix
d – A ;

13. Class Matrix // Minus Operator
Matrix operator - ( Matrix & m ) const ;
Matrix operator - ( double d ) const ;
friend Matrix operator - ( double d , Matrix & m ) ;

14. A * B ;
Where A and B are both matrices

15. d is a variable of type double ‘A’ is an object of a class Matrix
A * d ;

16. d is a variable of type double ‘a’ is an object of a class Matrix
d * A ;

17. Class Matrix // Multiplication Operator
Matrix operator * ( const Matrix & m ) ;
Matrix operator * ( double d ) const ;
friend Matrix operator * ( const double d , const Matrix & m ) ;

18. ‘A’ is an object of a class Matrix d is a variable of type double
A / d ;

19. Class Matrix // Division Operator
Matrix operator / ( const double d ) ;

20. Example // Where m is a matrix
// Stream Insertion and Extraction Operator
cin >> m ;
// Where m is a matrix

21. Class Matrix // Stream Insertion and Extraction Operator
friend istream & operator >> ( istream & , Matrix & ) ;
friend ifstream & operator >> ( ifstream & , Matrix & ) ;
friend istream & operator << ( istream & , Matrix & ) ;
friend ifstream & operator << ( ifstream & , Matrix & ) ;

22. Class Matrix const Matrix & operator = ( const Matrix & m ) ;
const Matrix & transpose ( void ) ;

23. Class Matrix
Matrix :: Matrix ( int row , int col ) // Default Constructor {
numRows = row ;
numCols = col ;
elements = new ( double * ) [ numRows ] ;
for ( int i = 0 ; i < numRows ; i ++ )
elements [ i ] = new double [ numCols ] ;
for ( int j = 0 ; j < numCols ; j ++ )
elements [ i ] [ j ] = 0.0 ; }

24. Matrix A ( B ) ;

25. Matrix A = B ;

26. Class Matrix Matrix :: Matrix ( const Matrix & m ) {
numRows = m.numRows ;
numCols = m.numCols ;
elements = new ( double * ) [ numRows ] ;
for ( int i = 0 ; i < numRows ; i ++ )
elements [ i ] = new double [ numCols ] ;
for ( int j = 0 ; j < numCols ; j ++ )
elements [ i ] [ j ] = m.elements [ i ] [ j ] ; }

27. Class Matrix
Matrix :: ~ Matrix ( void ) {
delete [ ] elements ; }

28. Class Matrix int Matrix :: getRows ( ) const { return numRows ; }
int Matrix :: getCols ( ) const
return numCols ;

29. Class Matrix void Matrix :: output ( ostream & os ) const {
// Print first row with special characters
os.setf ( ios :: showpoint ) ;
os.setf ( ios :: fixed , ios :: floatfield ) ;
os << ( char ) 218 ;
for ( int j = 0 ; j < numCols ; j ++ )
os << setw ( 10 ) << " “ ;
os << ( char ) 191 << "\n" ;

30. Class Matrix // Print remaining rows with vertical bars only
for ( int i = 0 ; i < numRows ; i ++ ) {
os << ( char ) 179 ;
for ( int j = 0 ; j < numCols ; j ++ )
os << setw ( 10 ) << setprecision ( 2 ) << elements [ i ] [ j ] ;
os << ( char ) 179 << "\n" ; }

31. Class Matrix // Print last row with special characters
os << ( char ) 192 ;
for ( int j = 0 ; j < numCols ; j ++ )
os << setw ( 10 ) << " " ;
os << ( char ) 217 << "\n" ; }

32. Class Matrix void Matrix :: output ( ofstream & os ) const {
os.setf ( ios :: showpoint ) ;
os.setf ( ios :: fixed , ios :: floatfield ) ;
os << numRows << " " << numCols << "\n" ;
for ( int i = 0 ; i < numRows ; i ++ )
for ( int j = 0 ; j < numCols ; j ++ )
os << setw ( 6 ) << setprecision ( 2 ) << elements [ i ] [ j ] ;
os << "\n" ; }

33. Class Matrix const Matrix & Matrix :: input ( istream & is ) {
cout << "Input Matrix size: " << numRows << " rows by " << numCols << " columns \n" ;
for ( int i = 0 ; i < numRows ; i ++ )
cout << "Please enter " << numCols << " values separated by spaces for row no." << i+1 << ": " ;
for ( int j = 0 ; j < numCols ; j ++ )
cin >> elements [ i ] [ j ] ; }
return * this ;

34. Class Matrix const Matrix & Matrix :: input ( ifstream & is ) {
int Rows , Cols ;
is >> Rows ;
is >> Cols ;
if ( Rows > 0 && Cols > 0 )
Matrix temp ( Rows , Cols ) ;
* this = temp ;
for ( int i = 0 ; i < numRows ; i ++ )
for ( int j = 0 ; j < numCols ; j ++ )
is >> elements [ i ] [ j ] ; }
return * this ;

35. Class Matrix const Matrix & Matrix :: transpose ( ) {
if ( numRows == numCols ) // Square Matrix
double temp ;
for ( int i = 0 ; i < numRows ; i ++ )
for ( int j = i + 1 ; j < numCols ; j ++ )
temp = elements [ i ] [ j ];
elements [ i ] [ j ] = elements [ j ] [ i ] ;
elements [ j ] [ i ] = temp ; }

36. Class Matrix else { Matrix temp(numCols, numRows);
for ( int i = 0 ; i < numRows ; i ++ )
for ( int j = 0 ; j < numCols ; j ++ )
temp.elements [ j ] [ i ] = elements [ i ] [ j ] ; }
* this = temp ;
return * this ;