antisymtensor.cc

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/*! \file
 *  \brief Compute anti-symmetric tensors
 */
 
#include "chromabase.h"
#include "util/ferm/antisymtensor.h"
 
namespace Chroma 
{
 
  //! Anonymous namespace
  /*! \ingroup ferm */
  namespace
  {
    multi3d<int> antisym_tensor3d;
    bool initP = false;
 
 
    //! Init gamma matrix multiplication table factors
    /*!
     * \ingroup ferm
     */
    void antiSymTensor3dInit()
    {
      START_CODE();
 
      antisym_tensor3d.resize(3,3,3);
      antisym_tensor3d = 0;
 
      // d = \epsilon^{i,j,k}
      // Permutations: +(0,1,2)+(1,2,0)+(2,0,1)-(1,0,2)-(0,2,1)-(2,1,0)
 
      antisym_tensor3d(0,1,2) = 1;
      antisym_tensor3d(1,2,0) = 1;
      antisym_tensor3d(2,0,1) = 1;
 
      antisym_tensor3d(1,0,2) = -1;
      antisym_tensor3d(0,2,1) = -1;
      antisym_tensor3d(2,1,0) = -1;
  
      initP = true;
 
      END_CODE();
    }
  } // end namespace
 
 
  //! Return 3d symmetric tensor
  /*!
   * \ingroup ferm
   *
   * \return  \f$\epsilon_{ijk}\f$
   */
  int antiSymTensor3d(int i, int j, int k)
  {
    if (! initP)
      antiSymTensor3dInit();
 
    if (i < 0 || i > 2 || j < 0 || j > 2 || k < 0 || k > 2)
    {
      QDPIO::cerr << __func__ << ": indices out of bounds: i,j,k=" 
                  << i << " " << j << " " << k << std::endl;
      QDP_abort(1);
    }
 
    return antisym_tensor3d(i,j,k);
  }
 
}  // end namespace Chroma