Tensor4.h

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// $Id$
//==============================================================================
//==============================================================================
 
#ifndef _TENSOR4_H
#define _TENSOR4_H
 
#include <vector>
#include <iostream>
 
 
class Tensor4
{
protected:
  typedef unsigned short int t_ind; 
 
  t_ind             n; 
  t_ind             m; 
  std::vector<Real> v; 
 
  virtual void redim(t_ind nsd) { n = nsd; m = n*n; }
 
  virtual std::ostream& print(std::ostream& os) const;
 
private:
  inline t_ind index(t_ind i, t_ind j, t_ind k, t_ind l) const
  {
    return i-1 + n*(j-1 + n*(k-1 + n*(l-1)));
  }
 
public:
  Tensor4(t_ind nsd = 3, Real scale = Real(1), bool makeJ = false);
  Tensor4(const std::vector<Real>& x, t_ind nsd = 3);
 
  void zero() { std::fill(v.begin(),v.end(),Real(0)); }
 
  operator const std::vector<Real>&() const { return v; }
  operator std::vector<Real>&() { return v; }
 
  const Real* ptr() const { return &v.front(); }
 
  const Real& operator()(t_ind i, t_ind j, t_ind d, t_ind l) const;
  Real& operator()(t_ind i, t_ind j, t_ind k, t_ind l);
 
  Tensor4& operator=(const Tensor4& T);
  Tensor4& operator=(Real val);
 
  Tensor4& operator+=(Real val);
 
  friend std::ostream& operator<<(std::ostream& os, const Tensor4& T)
  {
    return T.print(os);
  }
};
 
 
class SymmTensor4 : public Tensor4
{
protected:
  virtual void redim(t_ind nsd);
 
  virtual std::ostream& print(std::ostream& os) const;
 
private:
  inline t_ind index(t_ind i, t_ind j) const
  {
    if (i == j)
      return i-1; // diagonal term
    else if (n == 2)
      return 2;   // off-diagonal term (2D)
    else if (n == 1)
      return 0;
 
    if (i == j+1 || i+2 == j) std::swap(i,j);
    return i+2; // upper triangular term (3D)
  }
 
public:
  SymmTensor4(t_ind nsd = 3, bool makeJ = false);
  SymmTensor4(const std::vector<Real>& x, t_ind nsd = 3);
 
  const Real& operator()(t_ind i, t_ind j, t_ind d, t_ind l) const;
  Real& operator()(t_ind i, t_ind j, t_ind k, t_ind l);
};
 
#endif