lopishift.h

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// -*- C++ -*-
#ifndef __lopishift_h__
#define __lopishift_h__
 
/*! \file A linear operator scaled by i sigma where sigma is a Real shift */
 
#include "handle.h"
#include "linearop.h"
 
namespace Chroma {
 
  template<typename T, typename C>
  class lopishift : public LinearOperator<T>
  {
  public:
 
    //! Initialized from pointer
    lopishift(LinearOperator<T>* p, const C& s) : M(p), shift_fact(s) {}
    
    lopishift(Handle<LinearOperator<T> > p, const C& s) : M(p), shift_fact(s) {}
 
    ~lopishift(){};
 
    //! Subset comes from underlying operator
    inline const Subset& subset() const {return M->subset();}
    
    virtual unsigned long nFlops() const {
      return M->nFlops() + 4*Nc*Ns*(M->subset()).siteTable().size();
    }
 
    //! Apply the operator onto a source std::vector
    /*! For this operator, the sign is ignored */
    inline void operator() (T& chi, const T& psi, enum PlusMinus isign) const
      {
        const Subset& sub = M->subset();
        (*M)(chi, psi, isign);
        T tmp;
        tmp[sub] = Gamma(15)*timesI(psi);
        if( isign == PLUS) {
          chi[sub] += shift_fact*tmp; // (M + i shift) psi
        }
        else {
          chi[sub] -= shift_fact*tmp; // (M - i shift) psi
        }
      }
 
  private:
    Handle< LinearOperator<T> > M;
    const C& shift_fact;
  };
}
#endif