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[(1+n)*n/2];
  
  //////// constructor ////////
  dsymatrix_small(){;}
  ~dsymatrix_small(){;}
  
  //////// function ////////
  double& operator()(const long& i, const long& j){
    const long I(max(i,j)), J(min(i,j));
    return array[J*(2*n+I-J)/2 +I-J];
  }
  double  operator()(const long& i, const long& j) const{
    const long I(max(i,j)), J(min(i,j));
    return array[J*(2*n+I-J)/2 +I-J];
  }

  dsymatrix_small<n>& set(const long& i, const long& j, const double& v){
    (*this)(i,j)=v;
    return *this;
  }
  
  
  //long get_m(){ return n; }
  //long get_n(){ return n; }
  dsymatrix_small<n>& zero(){
    for(long k=0; k<(1+n)*n/2; k++){array[k]=0.;}
    return *this;
  }
  dsymatrix_small<n>& identity(){
    zero();
    for(long k=0; k<n; k++){ (*this)(k,k)=1.; }
    return *this;
  }
};