// -*- mode: C++ -*- /* Copyright (C) 2007 Christian Holm Christensen * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 * USA */ /** @file @brief Declaration of a Harmonic class */ //____________________________________________________________________ // // Calculate the nth order harmonic. // Input is the phis of the observations, // and the resolution of the event plane. // The class derives from AliFMDFlowStat to easy calculating the mean // and the square variance of the harmonic. #ifndef ALIFMDFLOWHARMONIC_H #define ALIFMDFLOWHARMONIC_H #include #include class TBrowser; /** @defgroup a_basic Basic classes for doing Flow analysis. @brief This group of class handles the low-level stuff to do flow analysis. @ingroup FMD_flow */ //______________________________________________________ /** @class AliFMDFlowHarmonic flow/AliFMDFlowHarmonic.h @brief Calculate the @f$n^{th}@f$ order harmonic @ingroup a_basic Calculate the @f$n^{th}@f$ order harmonic, given by @f{eqnarray*} v_n &=& \frac{v_n^{obs}}{R}\\ v_n^{obs} &=& \frac1M\sum_i^M\cos(n (\varphi_i - \Psi)) @f} where @f$R@f$ is the resolution, @f$i@f$ runs over all @f$M@f$ observations of @f$\varphi_i@f$ in all events, and @f$\Psi@f$ is the estimated event plane. The error on the corrected value is given by @f{eqnarray*} \delta^2v_n & = & \left(\frac{dv_n}{dv_n^{obs}}\right)^2\delta^2 v_n^{obs} + \left(\frac{dv_n}{dR}\right)^2\delta^2R \\ & = & \frac{\delta^2v_n^{obs} R^2 + \delta^2R (v_n^{obs})^2} {R^4} @f} */ class AliFMDFlowHarmonic : public AliFMDFlowStat { public: /** Constructor @param n Order of the harmonic */ AliFMDFlowHarmonic(UShort_t n=0); /** Destructor */ virtual ~AliFMDFlowHarmonic() {} /** Copy constructor @param o Object to copy from. */ AliFMDFlowHarmonic(const AliFMDFlowHarmonic& o); /** Assignment operator @param o Object to assign from @return Reference to this object. */ AliFMDFlowHarmonic& operator=(const AliFMDFlowHarmonic& o); /** @{ @name Processing */ /** Add a data point @param phi The absolute angle @f$\varphi \in[0,2\pi]@f$ @param psi The event plane angle @f$\Psi \in[0,2\pi] @f$ @param weight The weight of the observation */ void Add(Double_t phi, Double_t psi, Double_t weight=1); /** @} */ /** @{ @name Information */ /** Get the harmonic. @param r Event plane resolution @param er2 Square error on event plane resolution @param e2 On return the square error @return The harmonic value */ Double_t Value(Double_t r, Double_t er2, Double_t& e2) const; /** Get the order of the harmonic */ UShort_t Order() const { return fOrder; } /** @} */ /** @{ @name Utility */ /** This is a folder */ Bool_t IsFolder() const { return kTRUE; } /** Browse this object */ void Browse(TBrowser* b); /** Print content */ void Print(Option_t* option="") const; /** @} */ /** @{ @name histograms */ /** @return Contrib histogram */ const TH1& ContribHistogram() const { return fContrib; } /** @return Phi histogram */ const TH1& PhiHistogram() const { return fPhi; } /** @return Nphi histogram */ const TH1& NPhiHistogram() const { return fNPhi; } /** @return Weight histogram */ const TH1& WeightHistogram() const { return fWeight; } /** @} */ protected: /** the order */ UShort_t fOrder; // Order /** Histogram of angles */ TH1D fPhi; /** Histogram of angles */ TH1D fNPhi; /** Histogram of weights */ TH1D fWeight; /** cos(n(phi-psi)) vs (phi-psi) */ TH2D fContrib; /** Define for ROOT I/O */ ClassDef(AliFMDFlowHarmonic,1); }; #endif // // EOF //