DifRotation.cxx

Go to the documentation of this file.

//--------------------------------------------------------------------------
// File and Version Information:
//  $Id: DifRotation.cxx,v 1.2 2009/12/23 02:59:56 zhangy Exp $
//
// Description:
//  Class Implementation for |DifRotation|
//      Rotates things
// Environment:
//  Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author List:
//  A. Snyder
//
// Copyright Information:
//  Copyright (C) 1996  SLAC
//
// History:
//  Migration for BESIII MDC
//
//------------------------------------------------------------------------
 
#include "MdcRecoUtil/DifRotation.h"
 
DifRotation::DifRotation()
    : _xnew( 1.0, 0.0, 0.0 ), _ynew( 0.0, 1.0, 0.0 ), _znew( 0.0, 0.0, 1.0 ) {}
 
DifRotation::DifRotation( const DifNumber& alpha, const DifNumber& beta,
                          const DifNumber& gamma ) {
 
  // active transformation  - move the vector (reverse sines)
  DifNumber calpha = cos( alpha );
  DifNumber salpha = -sin( alpha );
  DifNumber cbeta  = cos( beta );
  DifNumber sbeta  = -sin( beta );
  DifNumber cgamma = cos( gamma );
  DifNumber sgamma = -sin( gamma );
 
  _xnew.x = cbeta * calpha * cgamma - salpha * sgamma;
  _xnew.y = cbeta * salpha * cgamma + calpha * sgamma;
  _xnew.z = -sbeta * cgamma;
 
  _ynew.x = -cbeta * calpha * sgamma - salpha * cgamma;
  _ynew.y = -cbeta * salpha * sgamma + calpha * cgamma;
  _ynew.z = sbeta * sgamma;
 
  _znew.x = sbeta * calpha;
  _znew.y = sbeta * salpha;
  _znew.z = cbeta;
}
 
DifRotation::DifRotation( const DifVector& xp, const DifVector& yp, const DifVector& zp )
    : _xnew( xp ), _ynew( yp ), _znew( zp ) {}
 
DifRotation::DifRotation( const DifVector& xp, const DifVector& yp )
    : _xnew( xp ), _ynew( yp ), _znew() {
  _znew = cross( _xnew, _ynew );
}
 
int DifRotation::fail() const { return 0; }
 
void DifRotation::rotate( DifVector& v ) const {
  DifNumber xcomp = xnew() * v;
  DifNumber ycomp = ynew() * v;
  DifNumber zcomp = znew() * v;
  v.x             = xcomp;
  v.y             = ycomp;
  v.z             = zcomp;
}