Revision 716fb731a3c8c9b583235feddac21006994d9626 authored by Kyle Cranmer on 03 August 2011, 22:09:36 UTC, committed by Kyle Cranmer on 03 August 2011, 22:09:36 UTC
git-svn-id: http://root.cern.ch/svn/root/branches/v5-30-00-patches@40446 27541ba8-7e3a-0410-8455-c3a389f83636
1 parent 0db9ccb
RooEllipse.cxx
/*****************************************************************************
* Project: RooFit *
* Package: RooFitCore *
* @(#)root/roofitcore:$Id$
* Authors: *
* WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu *
* DK, David Kirkby, UC Irvine, dkirkby@uci.edu *
* *
* Copyright (c) 2000-2005, Regents of the University of California *
* and Stanford University. All rights reserved. *
* *
* Redistribution and use in source and binary forms, *
* with or without modification, are permitted according to the terms *
* listed in LICENSE (http://roofit.sourceforge.net/license.txt) *
*****************************************************************************/
//////////////////////////////////////////////////////////////////////////////
//
// BEGIN_HTML
// A RooEllipse is a two-dimensional ellipse that can be used to represent
// an error contour.
// END_HTML
//
#include "RooFit.h"
#include "RooEllipse.h"
#include "RooEllipse.h"
#include "TMath.h"
#include "RooMsgService.h"
#include "Riostream.h"
#include "TClass.h"
#include <math.h>
#include <assert.h>
ClassImp(RooEllipse)
//_____________________________________________________________________________
RooEllipse::RooEllipse()
{
// Default constructor
}
//_____________________________________________________________________________
RooEllipse::~RooEllipse()
{
// Destructor
}
//_____________________________________________________________________________
RooEllipse::RooEllipse(const char *name, Double_t x1, Double_t x2, Double_t s1, Double_t s2, Double_t rho, Int_t points)
{
// Create a 2-dimensional ellipse centered at (x1,x2) that represents the confidence
// level contour for a measurement with errors (s1,s2) and correlation coefficient rho.
// The resulting curve is defined as the unique ellipse that passes through these points:
//
// (x1+rho*s1,x2+s2) , (x1-rho*s1,x2-s2) , (x1+s1,x2+rho*s2) , (x1-s1,x2-rho*s2)
//
// and is described by the implicit equation:
//
// x*x 2*rho*x*y y*y
// ----- - --------- + ----- = 1 - rho*rho
// s1*s1 s1*s2 s2*s2
//
// The input parameters s1,s2 must be > 0 and also |rho| <= 1.
// The degenerate case |rho|=1 corresponds to a straight line and
// is handled as a special case.
SetName(name);
SetTitle(name);
if(s1 <= 0 || s2 <= 0) {
coutE(InputArguments) << "RooEllipse::RooEllipse: bad parameter s1 or s2 < 0" << endl;
return;
}
Double_t tmp= 1-rho*rho;
if(tmp < 0) {
coutE(InputArguments) << "RooEllipse::RooEllipse: bad parameter |rho| > 1" << endl;
return;
}
if(tmp == 0) {
// handle the degenerate case of |rho|=1
SetPoint(0,x1-s1,x2-s2);
SetPoint(1,x1+s1,x2+s2);
setYAxisLimits(x2-s2,x2+s2);
}
else {
Double_t r,psi,phi,u1,u2,xx1,xx2,dphi(2*TMath::Pi()/points);
for(Int_t index= 0; index < points; index++) {
phi= index*dphi;
// adjust the angular spacing of the points for the aspect ratio
psi= atan2(s2*sin(phi),s1*cos(phi));
u1= cos(psi)/s1;
u2= sin(psi)/s2;
r= sqrt(tmp/(u1*u1 - 2*rho*u1*u2 + u2*u2));
xx1= x1 + r*u1*s1;
xx2= x2 + r*u2*s2;
SetPoint(index, xx1, xx2);
if(index == 0) {
setYAxisLimits(xx2,xx2);
// add an extra segment to close the curve
SetPoint(points, xx1, xx2);
}
else {
updateYAxisLimits(xx2);
}
}
}
}
//_____________________________________________________________________________
void RooEllipse::printName(ostream& os) const
{
// Print name of ellipse on ostream
os << GetName() ;
}
//_____________________________________________________________________________
void RooEllipse::printTitle(ostream& os) const
{
// Print title of ellipse on ostream
os << GetName() ;
}
//_____________________________________________________________________________
void RooEllipse::printClassName(ostream& os) const
{
// Print class name of ellipse on ostream
os << IsA()->GetName() ;
}
//_____________________________________________________________________________
void RooEllipse::printMultiline(ostream& os, Int_t contents, Bool_t verbose, TString indent) const
{
// Print detailed multi line information on ellipse on ostreamx
RooPlotable::printMultiline(os,contents,verbose,indent);
for(Int_t index=0; index < fNpoints; index++) {
os << indent << "Point [" << index << "] is at (" << fX[index] << "," << fY[index] << ")" << endl;
}
}
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