expmat.cc

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/*! \file
 *  \brief Exponentiate a SU(n) lie algebra element by some method,
 */
 
#include "chromabase.h"
#include "util/gauge/expmat.h"
#include "util/gauge/expm12.h"
#include "util/gauge/expsu3.h"
#include "util/gauge/eeu1.h"
#include "util/gauge/eesu2.h"
#include "util/gauge/eesu3.h"
#include "util/gauge/reunit.h"
//#include "util/gauge/eesu3.h"
 
 
namespace Chroma { 
 
  namespace ExpMatEnv {
    static double time_spent = 0;
 
    double getTime() { return time_spent ; }
 
  }
 
 
//! Exponentiate a SU(n) lie algebra element by some method.
/*!
 * \ingroup gauge
 *
 * This routine is a driver for other routines. For example, expsu3
 * will exponentiate EFFICIENTLY an SU(3) matrix and, if desired,
 * check for errors in the truncation of the Taylor series.
 * The routine eesu3 EXACTLY exponentiates a SU(3) matrix. 
 *
 *  \param a        LatticeColorMatrix          (Modify)
 *  \param opt      Method of exponentiation    (Read)
 */
 
void expmat(LatticeColorMatrix& a,
            enum ExpMat_t opt)
{
  START_CODE();
  QDP::StopWatch swatch;
  swatch.reset();
  swatch.start();
 
  switch (Nc)
  {
  case 1:
    eeu1(a);
    break;
 
  case 2:
    eesu2(a);
    break;
 
  default:
    switch (opt)
    {
    case EXP_TWELFTH_ORDER:
      switch (Nc)
      {
      case 3:
        expsu3(a, REUNITARIZE_LABEL);
        break;
        
      default:
        expm12(a);
        break;
      }
      break;
 
    case EXP_EXACT:
      switch (Nc)
      {
      case 3:
        eesu3(a);
        break;
 
      default:
        QDPIO::cerr << __func__ << ": exact exponentation not implemented for this Nc=" << Nc << std::endl;
        QDP_abort(1);
      }
      break;
 
    default:
      QDPIO::cerr << __func__ << ": unknown option = " << opt << std::endl;
      QDP_abort(1);
    }
  }
 
  swatch.stop();
  ExpMatEnv::time_spent += swatch.getTimeInSeconds();
  END_CODE();
}
 
} // End namespace Chroma