CPPLapack Code

//=============================================================================
//! Base class for Small Real Double-precision Symmetric Matrix Class
class dsymatrix_small_base
{
public:
  //////// constructor ////////
  dsymatrix_small_base(){;}
  virtual ~dsymatrix_small_base(){;}
};

//=============================================================================
//! Samll Real Double-precision Symmetric Matrix Class
template<long n> class dsymatrix_small : public dsymatrix_small_base
{
public:
  //////// data ////////
  double array[(n*(n+1))/2];
  
  //////// constructor ////////
  dsymatrix_small(){;}
  dsymatrix_small(const double& x){
    for(long k=0; k<(n*(n+1))/2; k++){ array[k]=x; }
  }
  ~dsymatrix_small(){;}
  
  //////// function ////////
  double& operator()(const long& i, const long& j){
#ifdef  CPPL_DEBUG
    if(i<j){ std::cerr << "[ERROR]dsymatrix_small::operator(): i<j" << std::endl; exit(1); }
#endif
    //const long I(max(i,j)), J(min(i,j)); return array[(I*(I+1))/2 +J];
    return array[(i*(i+1))/2 +j];
  }
  
  double  operator()(const long& i, const long& j) const{
#ifdef  CPPL_DEBUG
    if(i<j){ std::cerr << "[ERROR]dsymatrix_small::operator(): i<j" << std::endl; exit(1); }
#endif
    //const long I(max(i,j)), J(min(i,j)); return array[(I*(I+1))/2 +J];
    return array[(i*(i+1))/2 +j];
  }
  
  //long get_m(){ return n; }
  //long get_n(){ return n; }
  dsymatrix_small<n>& zero(){
    for(long i=0; i<n; i++){ for(long j=0; j<=i; j++){ (*this)(i,j)=0.; } }
    return *this;
  }
  dsymatrix_small<n>& identity(){
    zero();
    for(long k=0; k<n; k++){ (*this)(k,k)=1.; }
    return *this;
  }
};

//=============================================================================
template<long n>
inline std::ostream& operator<<(std::ostream& s, const dsymatrix_small<n>& A)
{
  s << std::setiosflags(std::ios::showpos);
  for(long i=0; i<n; i++){
    for(long j=0;   j<=i; j++){ s << " " << A(i,j) << " "<< std::flush; }
    for(long j=i+1; j<n;  j++){ s << "{" << A(j,i) << "}" << std::flush; }
    s << std::endl;
  }
  return s;
}