MdcSegInfoCsmc.cxx

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//--------------------------------------------------------------------------
// File and Version Information:
//      $Id: MdcSegInfoCsmc.cxx,v 1.3 2009/12/16 09:02:47 zhangy Exp $
//
// Description:
//
// Environment:
//      Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Authors:
//
// Copyright (C)  1996  The Board of Trustees of
//
// History:
//  Migration for BESIII MDC
// The Leland Stanford Junior University.  All Rights Reserved.
//------------------------------------------------------------------------
// #include "BaBar/BaBar.h"
#include "MdcTrkRecon/MdcSegInfoCsmc.h"
#include "MdcGeom/BesAngle.h"
#include "MdcGeom/MdcSuperLayer.h"
#include "MdcTrkRecon/MdcSeg.h"
#include "MdcTrkRecon/mdcTwoInv.h"
#include <assert.h>
#include <math.h>
// #include "ErrLogger/ErrLog.h"
using std::endl;
 
//--------------------------------------------------------------------------
bool MdcSegInfoCsmc::parIsAngle( int i ) const {
  //---------------------------------------------------------------------------
  assert( i >= 0 && i < 2 );
  return ( 0 != i ); // i.e., parameter 1 is an angle
}
//------------------------------------------------------------------
void MdcSegInfoCsmc::calcStraight( double phi, double slope, double rad,
                                   const double* inErr ) {
  //------------------------------------------------------------------
  // Load the segment info obj with phi0 and d0 values, calc. assuming
  // the segments lie on straight tracks.
  //
  // d0 defined to be positive for tracks that intercept x axis on positive
  //   phi (neg x) side of origin.  At least that's what I claim. */
 
  // error matrix conversion:
  //   Vij(f) = SUM(n,m) ( d(fi)/d(yn) * d(fj)/d(ym) * Vnm(y) )
  //   The derivatives are calculated from:
  //       d0 = r**2 * slope / sqrt( 1 + r**2 * slope**2 )   &
  //       phi0 = phiseg - asin(d0 / r)
 
  //    d0ovSlope = r**2/sqrt(1 + slope**2 * r**2) = d0 / slope
  //    d0ovrad = d0/r
  //    d0ovradsq = (d0/r)**2
  //    dphi0dphi = d(phi0)/d(seg-phi)
  //    dphi0ds   = d(phi0)/d(seg-slope)
  //    dd0ds   = d(d0)/d(seg-slope)
  //    dd0dphi = 0
 
  double d0ovSlope = -rad * rad / sqrt( 1. + slope * slope * rad * rad );
  double d0        = slope * d0ovSlope;
  _par0            = d0;
 
  double d0ovRad = d0 / rad;
  // Don't blow away arcsine:
  d0ovRad =
      ( d0ovRad > 1.0 || d0ovRad < -1.0 ) ? ( d0ovRad + 0.00001 ) / fabs( d0ovRad ) : d0ovRad;
  BesAngle phi0 = phi - asin( d0ovRad );
  _par1         = phi0.posRad();
 
  // Error matrix (anal calculation).
  //  double dphi0dphi = 1.;
  double dphi0ds = -d0ovSlope * sqrt( 1. - d0ovRad * d0ovRad ) / rad;
  double dd0ds   = d0ovSlope * ( 1. - d0ovRad * d0ovRad );
 
  // d0:
  _errmat[0] = inErr[2] * dd0ds * dd0ds;
  if ( _errmat[0] < 0. ) _errmat[0] = 0.;
 
  // phi0:
  _errmat[2] = inErr[2] * dphi0ds * dphi0ds + inErr[0] + inErr[1] * 2. * dphi0ds;
  if ( _errmat[2] < 0. ) _errmat[2] = 0.;
  // phi0|d0:
  _errmat[1] = inErr[2] * dd0ds * dphi0ds + inErr[1] * dd0ds;
 
  int error = mdcTwoInv( _errmat, _inverr );
  if ( error )
  {
    std::cout << " ErrMsg(warning) "
              << "Failed to invert matrix -- MdcSegInfo::calcStraight" << endl
              << _errmat[0] << " " << _errmat[1] << " " << _errmat[2] << std::endl;
  }
}
 
//------------------------------------------------------------------
void MdcSegInfoCsmc::calcStraight( const MdcSeg* parentSeg ) {
  //------------------------------------------------------------------
  double        slope  = parentSeg->slope();
  double        radius = parentSeg->superlayer()->rad0();
  double        phi    = parentSeg->phi();
  const double* inErr  = parentSeg->errmat();
 
  calcStraight( phi, slope, radius, inErr );
}
 
//------------------------------------------------------------------
double MdcSegInfoCsmc::sigPhi0() const {
  //------------------------------------------------------------------
  return sqrt( _errmat[2] );
}
//------------------------------------------------------------------
double MdcSegInfoCsmc::sigD0() const {
  //------------------------------------------------------------------
  return sqrt( _errmat[0] );
}