ParabolaFit Class Reference

#include <ParabolaFit.h>

Classes
struct	Column
struct	Point
struct	Result

Public Member Functions
void	addPoint (double x, double y)
void	addPoint (double x, double y, double weight)
double	chi2 () const
int	dof () const
void	fixParC (double val)
double	parA () const
	ParabolaFit ()
double	parB () const
double	parC () const
const Result &	result (bool doErrors) const
void	skipErrorCalculationByDefault ()
double	varAA () const
double	varAB () const
double	varAC () const
double	varBB () const
double	varBC () const
double	varCC () const

Private Member Functions
double	det (const Column &c1, const Column &c2, const Column &c3) const
double	det (const Column &c1, const Column &c2) const
double	fun (double x) const

Private Attributes
bool	doErr
bool	hasErrors
bool	hasFixedParC
bool	hasValues
bool	hasWeights
std::vector< Point >	points
Result	theResult

Detailed Description

The parabola fit y = parA + parB * x + parC * x*x see: R.L. Gluckstern, NIM 24 (1963) 381

Definition at line 12 of file ParabolaFit.h.

Constructor & Destructor Documentation

ParabolaFit::ParabolaFit ( )

inline

Definition at line 16 of file ParabolaFit.h.

                : 
      doErr(true), hasFixedParC(false), hasValues(false), hasErrors(false), hasWeights(true) { }

Member Function Documentation

void ParabolaFit::addPoint	(	double	x,
		double	y
	)

Definition at line 6 of file ParabolaFit.cc.

Referenced by ConformalMappingFit::ConformalMappingFit().

{
  hasWeights = false;
  addPoint(x,y,1.);
}

void ParabolaFit::addPoint	(	double	x,
		double	y,
		double	weight
	)

Definition at line 12 of file ParabolaFit.cc.

References AlCaHLTBitMon_ParallelJobs::p, vdt::x, and detailsBasic3DVector::y.

{
  hasValues = false;
  hasErrors = false;
  Point p = {x,y,w};
  points.push_back(p);
}

double ParabolaFit::chi2

(

void

)

const

Definition at line 104 of file ParabolaFit.cc.

References funct::sqr().

Referenced by ConformalMappingFit::chi2().

{
  double mychi2 = 0.;
  for ( vector<Point>::const_iterator 
      ip = points.begin(); ip != points.end(); ip++) {
     mychi2 += ip->w * sqr(ip->y - fun(ip->x)); 
  }
  return mychi2;
}

double ParabolaFit::det ( const Column &  c1, const Column &  c2, const Column &  c3  ) const

private

Definition at line 126 of file ParabolaFit.cc.

References ParabolaFit::Column::r1, ParabolaFit::Column::r2, and ParabolaFit::Column::r3.

{
  return   c1.r1 * c2.r2 * c3.r3
         + c2.r1 * c3.r2 * c1.r3
         + c3.r1 * c1.r2 * c2.r3
         - c1.r3 * c2.r2 * c3.r1
         - c2.r3 * c3.r2 * c1.r1
         - c3.r3 * c1.r2 * c2.r1;
}

double ParabolaFit::det ( const Column &  c1, const Column &  c2  ) const

private

Definition at line 137 of file ParabolaFit.cc.

References ParabolaFit::Column::r1, and ParabolaFit::Column::r2.

{
  return c1.r1*c2.r2 - c1.r2*c2.r1;
}

int ParabolaFit::dof

(

)

const

Definition at line 119 of file ParabolaFit.cc.

{
  int nPar = 3; if (hasFixedParC) nPar--;
  int nDof = points.size() - nPar;
  return (nDof > 0) ? nDof : 0;
}

void ParabolaFit::fixParC ( double  val )

inline

Definition at line 23 of file ParabolaFit.h.

References hasFixedParC, ParabolaFit::Result::parC, and theResult.

Referenced by ConformalMappingFit::fixImpactParmaeter().

{ hasFixedParC = true; theResult.parC = val; }

double ParabolaFit::fun ( double  x ) const

private

Definition at line 114 of file ParabolaFit.cc.

References vdt::x.

{
   return theResult.parA + theResult.parB*x + theResult.parC*x*x;
}

double ParabolaFit::parA ( ) const

inline

Definition at line 27 of file ParabolaFit.h.

References doErr, hasValues, ParabolaFit::Result::parA, result(), and theResult.

Referenced by ConformalMappingFit::charge(), and ConformalMappingFit::curvature().

{ if(!hasValues) result(doErr); return theResult.parA; }

double ParabolaFit::parB ( ) const

inline

Definition at line 28 of file ParabolaFit.h.

References doErr, hasValues, ParabolaFit::Result::parB, result(), and theResult.

Referenced by ConformalMappingFit::directionPhi().

{ if(!hasValues) result(doErr); return theResult.parB; }

double ParabolaFit::parC ( ) const

inline

Definition at line 29 of file ParabolaFit.h.

References doErr, hasValues, ParabolaFit::Result::parC, result(), and theResult.

Referenced by ConformalMappingFit::impactParameter().

{ if(!hasValues) result(doErr); return theResult.parC; }

const ParabolaFit::Result & ParabolaFit::result

(

bool

doErrors

)

const

Definition at line 20 of file ParabolaFit.cc.

References funct::pow(), funct::sqr(), w(), vdt::x, and detailsBasic3DVector::y.

Referenced by parA(), parB(), parC(), varAA(), varAB(), varAC(), varBB(), varBC(), and varCC().

{
  if (hasErrors)  return theResult;
  if (hasValues && !doErrors) return theResult;

  double F0,  F1,  F2,  F3,  F4,  F0y,  F1y,  F2y;
         F0 = F1 = F2 = F3 = F4 = F0y = F1y = F2y = 0.;

  typedef vector<Point>::const_iterator IT;
  for (IT ip = points.begin(); ip != points.end(); ip++) {
 
    double pow;
    double x = ip->x;
    double y = ip->y;
    double w = ip->w;

                F0 += w;         F0y += w*y;   
                F1 += w*x;       F1y += w*x*y;
    pow = x*x;  F2 += w*pow;     F2y += w*pow*y;    // x^2
    pow *= x;   F3 += w*pow;                        // x^3
    pow *= x;   F4 += w*pow;                        // x^4
  }

  Column cA = { F0, F1, F2 };
  Column cB = { F1, F2, F3 };
  Column cC = { F2, F3, F4 };
  Column cY = { F0y, F1y, F2y };

  double det0 = det(cA, cB, cC);

  if ( !hasFixedParC) {
  theResult.parA = det(cY, cB, cC) / det0;
  theResult.parB = det(cA, cY, cC) / det0;
  theResult.parC = det(cA, cB, cY) / det0;
  } else {
    Column cCY = {F0y-theResult.parC*F2, F1y-theResult.parC*F3, F2y-theResult.parC*F4};
    double det0C   = det(cA, cB);
    theResult.parA = det(cCY, cB) / det0C;
    theResult.parB = det(cA, cCY) / det0C;
  } 

//  std::cout <<" result: A="<<theResult.parA<<" B="<<theResult.parB<<" C="<<theResult.parC<<endl; 
  double vAA,  vBB,  vCC,  vAB,  vAC,  vBC;
         vAA = vBB = vCC = vAB = vAC = vBC = 0.;

  hasValues = true;
  if (!doErrors) return theResult;

  if( !hasWeights &&  dof() > 0) {
//     cout <<" CHI2: " << chi2() <<" DOF: " << dof() << endl;
     double scale_w = 1./chi2()/dof();
     for (IT ip = points.begin(); ip != points.end(); ip++) ip->w *= scale_w; 
//     cout <<" CHI2: " << chi2() <<" DOF: " << dof() << endl;
  }
  
  for (IT ip = points.begin(); ip != points.end(); ip++) {

    double w = ip->w;
    Column cX = {1., ip->x, sqr(ip->x) };

    double dXBC = det(cX, cB, cC);
    double dAXC = det(cA, cX, cC);
    double dABX = det(cA, cB, cX);

    vAA += w * sqr(dXBC);
    vBB += w * sqr(dAXC);
    vCC += w * sqr(dABX);
    vAB += w * dXBC * dAXC;
    vAC += w * dXBC * dABX;
    vBC += w * dAXC * dABX;
  }
   
  theResult.varAA = vAA/sqr(det0);
  theResult.varBB = vBB/sqr(det0);
  theResult.varCC = vCC/sqr(det0);
  theResult.varAB = vAB/sqr(det0);
  theResult.varAC = vAC/sqr(det0);
  theResult.varBC = vBC/sqr(det0);

  hasErrors = true;
  return theResult;
}

void ParabolaFit::skipErrorCalculationByDefault ( )

inline

Definition at line 22 of file ParabolaFit.h.

References doErr.

Referenced by ConformalMappingFit::skipErrorCalculation().

{ doErr = false; }

double ParabolaFit::varAA ( ) const

inline

Definition at line 30 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varAA.

Referenced by ConformalMappingFit::curvature().

{ if(!hasErrors) result(true); return theResult.varAA; }

double ParabolaFit::varAB ( ) const

inline

Definition at line 33 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varAB.

{ if(!hasErrors) result(true); return theResult.varAB; }

double ParabolaFit::varAC ( ) const

inline

Definition at line 34 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varAC.

{ if(!hasErrors) result(true); return theResult.varAC; }

double ParabolaFit::varBB ( ) const

inline

Definition at line 31 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varBB.

Referenced by ConformalMappingFit::directionPhi().

{ if(!hasErrors) result(true); return theResult.varBB; }

double ParabolaFit::varBC ( ) const

inline

Definition at line 35 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varBC.

{ if(!hasErrors) result(true); return theResult.varBC; }

double ParabolaFit::varCC ( ) const

inline

Definition at line 32 of file ParabolaFit.h.

References hasErrors, result(), theResult, and ParabolaFit::Result::varCC.

Referenced by ConformalMappingFit::impactParameter().

{ if(!hasErrors) result(true); return theResult.varCC; }

Member Data Documentation

bool ParabolaFit::doErr

private

Definition at line 50 of file ParabolaFit.h.

Referenced by parA(), parB(), parC(), and skipErrorCalculationByDefault().

bool ParabolaFit::hasErrors

mutableprivate

Definition at line 51 of file ParabolaFit.h.

Referenced by varAA(), varAB(), varAC(), varBB(), varBC(), and varCC().

bool ParabolaFit::hasFixedParC

private

Definition at line 50 of file ParabolaFit.h.

Referenced by fixParC().

bool ParabolaFit::hasValues

mutableprivate

Definition at line 51 of file ParabolaFit.h.

Referenced by parA(), parB(), and parC().

bool ParabolaFit::hasWeights

private

Definition at line 52 of file ParabolaFit.h.

std::vector<Point> ParabolaFit::points

mutableprivate

Definition at line 49 of file ParabolaFit.h.

Result ParabolaFit::theResult

mutableprivate

Definition at line 53 of file ParabolaFit.h.

Referenced by fixParC(), parA(), parB(), parC(), varAA(), varAB(), varAC(), varBB(), varBC(), and varCC().