single_phase.cc

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/*! \file
 *  \brief Compute a single phase factor
 */
 
#include "chromabase.h"
#include "util/ft/single_phase.h"
 
namespace Chroma 
{
 
  //! A single exp(ip.x) phase used in hadron construction
  /*! @ingroup ft */
  LatticeComplex singlePhase(const multi1d<int>& t_srce, 
                             const multi1d<int>& sink_mom, 
                             int j_decay)
  {
    START_CODE();
 
    // Sanity checks
    if (j_decay < 0 || j_decay >= Nd)
    {
      QDPIO::cerr << __func__ << ": j_decay out of bounds" << std::endl;
      QDP_abort(1);
    }
 
    if (t_srce.size() != Nd)
    {
      QDPIO::cerr << __func__ << ": t_srce not of size = " << Nd << std::endl;
      QDP_abort(1);
    }
 
    if (sink_mom.size() != Nd-1)
    {
      QDPIO::cerr << __func__ << ": mom not of size = " << Nd-1 << std::endl;
      QDP_abort(1);
    }
 
    /*
     *  We now inject momentum at sink if required
     */
    LatticeReal p_dot_x = zero;
    bool nonzeroP = false;
    for(int mu=0, j=0; mu < Nd; mu++)
    {
      if (mu != j_decay)
      {
        if (sink_mom[j] != 0)
        {
          nonzeroP = true;
          p_dot_x += (Layout::latticeCoordinate(mu) - t_srce[mu]) * sink_mom[j] 
            * twopi / Real(Layout::lattSize()[mu]);
        }
        j++;
      }
    }
 
    LatticeComplex phase;
 
    if (nonzeroP)
      phase = cmplx(cos(p_dot_x),sin(p_dot_x));
    else
      phase = 1.0;
 
    END_CODE();
 
    return phase;
  }
 
  LatticeComplex singlePhase(const multi1d<int>& t_srce, 
                             const multi1d<int>& sink_mom)
  {
    START_CODE();
 
    if (t_srce.size() != Nd)
    {
      QDPIO::cerr << __func__ << ": t_srce not of size = " << Nd << std::endl;
      QDP_abort(1);
    }
 
    if (sink_mom.size() != Nd)
    {
      QDPIO::cerr << __func__ << ": mom not of size = " << Nd << std::endl;
      QDP_abort(1);
    }
 
    /*
     *  We now inject momentum at sink if required
     */
    LatticeReal p_dot_x = zero;
    bool nonzeroP = false;
    for(int mu=0, j=0; mu < Nd; mu++)
    {
      if (sink_mom[mu] != 0)
        {
          nonzeroP = true;
          p_dot_x += (Layout::latticeCoordinate(mu) - t_srce[mu]) * sink_mom[mu]
            * twopi / Real(Layout::lattSize()[mu]);
        }
    }
 
    LatticeComplex phase;
 
    if (nonzeroP)
      phase = cmplx(cos(p_dot_x),sin(p_dot_x));
    else
      phase = 1.0;
 
    END_CODE();
 
    return phase;
  }
 
}  // end namespace Chroma