diagonalmatrix.h

datastucutre and algorithms, application, in C

// diagonal matrix
#ifndef diagonalMatrix_
#define diagonalMatrix_


#include "myExceptions.h"

using namespace std;

template<class T>
class diagonalMatrix 
{
   public:
      diagonalMatrix(int theN = 10);
      ~diagonalMatrix() {delete [] element;}
      T get(int, int) const;
      void set(int, int, const T&);
   private:
      int n;       // matrix dimension
      T *element;  // 1D array for diagonal elements
};

template<class T>
diagonalMatrix<T>::diagonalMatrix(int theN)
{// Constructor.
   // validate theN
   if (theN < 1)
       throw illegalParameterValue("Matrix size must be > 0");

   n = theN;
   element = new T [n];
}
  
template <class T>
T diagonalMatrix<T>::get(int i, int j) const
{// Return (i,j)th element of matrix.
   // validate i and j
   if (i < 1 || j < 1 || i > n || j > n)
       throw matrixIndexOutOfBounds();

   if (i == j)
      return element[i-1];   // diagonal element
   else
      return 0;              // nondiagonal element
}

template<class T>
void diagonalMatrix<T>::set(int i, int j, const T& newValue)
{// Store newValue as (i,j)th element.
   // validate i and j
   if (i < 1 || j < 1 || i > n || j > n)
       throw matrixIndexOutOfBounds();

   if (i == j)
     // save the diagonal value
      element[i-1] = newValue;
   else
      // nondiagonal value, newValue must be zero
      if (newValue != 0)
         throw illegalParameterValue
               ("nondiagonal elements must be zero");
}

#endif