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 //
 // APFEL++ 2017
 //
 // Author: Valerio Bertone: valerio.bertone@cern.ch
 //
 
 #pragma once
 
 #include <cmath>
 #include <vector>
 #include <array>
 
 namespace apfel
 {
   /**
    * @defgroup NumericalConstants Numerical constants
    * Collection of numerical constants often used
    * in the computations.
    */
   ///@{
   ///@}
 
   /**
    * @defgroup PertOrds Perturbative orders
    * Enumerators for the perturbative orders for both fixed order and
    * resummation.
    * @ingroup NumericalConstants
    */
   ///@{
   enum FixedOrderAccuracy: int {LO = 0, NLO = 1, NNLO = 2, NNNLO = 3, N4LO = 4};
   enum LogAccuracy: int {NNNLLp = -3, NNLLp = -2, NLLp = -1, LL = 0, NLL = 1, NNLL = 2, NNNLL = 3, N4LL = 4};
   ///@}
 
   /**
    * @defgroup PartonSpecies Partonic species
    * Enumerator for distinguishing different partonic species.
    * @ingroup NumericalConstants
    */
   ///@{
   enum PartonSpecies: int {UNKNOWN = -1, GLUON = 0, DOWNTYPEQUARK = 1, UPTYPEQUARK = 2, PHOTON = 4, CHARGEDLEPTON = 4, NEUTRINO = 5};
   ///@}
 
   /**
    * @defgroup MathConstants Mathematical constants
    * Collection of mathematical constants often used in the code.
    * @ingroup NumericalConstants
    */
   ///@{
   /**
    * @name Small numbers
    * @brief Small numbers used for cutoffs, integration accuracies, etc.
    */
   ///@{
   const double eps2  = 1e-2;
   const double eps3  = 1e-3;
   const double eps4  = 1e-4;
   const double eps5  = 1e-5;
   const double eps6  = 1e-6;
   const double eps7  = 1e-7;
   const double eps8  = 1e-8;
   const double eps9  = 1e-9;
   const double eps10 = 1e-10;
   const double eps11 = 1e-11;
   const double eps12 = 1e-12;
   const double eps13 = 1e-13;
   const double eps14 = 1e-14;
   const double eps15 = 1e-15;
   const double eps25 = 1e-25;
   ///@}
 
   /**
    * @name Gauss-Legendre quadrature
    * @brief Coordinates and weights of the Gauss-Legendre quadrature
    * with 8 and 16-point integration.
    */
   ///@{
   const std::array<std::vector<double>, 2> gl_x =
   {
     {
       std::vector<double>{0.1834346424956498, 0.5255324099163289, 0.7966664774136267, 0.9602898564975362},
       std::vector<double>{
         0.0950125098376374, 0.2816035507792589, 0.4580167776572273, 0.6178762444026437,
         0.7554044083550030, 0.8656312023878317, 0.9445750230732325, 0.9894009349916499
       }
     }
   };
   const std::array<std::vector<double>, 2> gl_w =
   {
     {
       std::vector<double>{0.3626837833783619, 0.3137066458778872, 0.2223810344533744, 0.1012285362903762},
       std::vector<double>{
         0.1894506104550684, 0.1826034150449235, 0.1691565193950025, 0.1495959888165767,
         0.1246289712555338, 0.0951585116824927, 0.0622535239386478, 0.0271524594117540
       }
     }
   };
   ///@}
 
   /**
    * @name Gauss-Kronrod quadrature
    * @brief Coordinates and weights of the Gauss-Kronrod quadrature
    * with 7 and 15-point integration.
    */
   ///@{
   const std::array<std::vector<double>, 2> gk_x =
   {
     {
       std::vector<double>{0.0000000000000000e+00, 4.0584515137739717e-01, 7.4153118559939444e-01, 9.4910791234275852e-01},
       std::vector<double>{
         0.0000000000000000e+00, 2.0778495500789847e-01, 4.0584515137739717e-01, 5.8608723546769113e-01,
         7.4153118559939444e-01, 8.6486442335976907e-01, 9.4910791234275852e-01, 9.9145537112081264e-01
       }
     }
   };
   const std::array<std::vector<double>, 2> gk_w =
   {
     {
       std::vector<double>{4.1795918367346939e-01, 3.8183005050511894e-01, 2.7970539148927667e-01, 1.2948496616886969e-01},
       std::vector<double>{
         2.0948214108472783e-01, 2.0443294007529889e-01, 1.9035057806478541e-01, 1.6900472663926790e-01,
         1.4065325971552592e-01, 1.0479001032225018e-01, 6.3092092629978553e-02, 2.2935322010529225e-02
       }
     }
   };
   ///@}
 
   /**
    * @name Numerical constants
    * @brief Definitions for recurrent constants.
    */
   ///@{
   const double Pi2    = M_PI * M_PI;
   const double FourPi = 4 * M_PI;
   const double emc    = 0.5772156649015329;
   const double zeta2  = 1.6449340668482264; // Pi2 / 6;
   const double zeta3  = 1.2020569031595943;
   const double zeta4  = 1.0823232337111382; // Pi2 * Pi2 / 90;
   const double zeta5  = 1.0369277551433699;
   const double zeta6  = 1.0173430619844491; // Pi2 * Pi2 * Pi2 / 945
   ///@}
 
   /**
    * @name QCD colour factors
    * The SU(3) Casimir's.
    */
   ///@{
   const double TR = 0.5;
   const double CF = 4. / 3.;
   const double CA = 3.;
   const double NC = 3.;
   ///@}
   ///@}
 
   /**
    * @defgroup PhysConstants Physical constants
    * Collection of physical constants often used in the code.
    * @ingroup NumericalConstants
    */
   ///@{
   /**
    * @name Quark charges
    * @brief Quark electric charges and their square (it also includes
    * sums of charges).
    */
   ///@{
   const double ed  = - 1. / 3.;
   const double eu  =   2. / 3.;
   const double ed2 =   1. / 9.;
   const double eu2 =   4. / 9.;
   const std::vector<double> QCh  = {ed,  eu,  ed,  eu,  ed,  eu};
   const std::vector<double> QCh2 = {ed2, eu2, ed2, eu2, ed2, eu2};
   const std::vector<double> SumCh2 = {0., 1./9., 5./9., 2./3., 10./9., 11./9., 5./3.};
   const std::vector<double> SumCh4 = {0., 1./81., 17./81., 18./81., 34./81., 35./81., 51./81.};
   ///@}
 
   /**
    * @name Flavour factors required by the N<SUP>3</SUP>LO DIS coefficient functions
    * @brief Their definition can be found in Tab. 2 (page 8) of
    * https://arxiv.org/pdf/hep-ph/0504242v1.pdf.
    */
   ///@{
   const std::vector<double> fl11ns = {-1, 0.5, 0, 0.5, 0.2, 0.5};
   const std::vector<double> fl11sg = {1, 0.1, 0, 0.1, 0.018181818, 0.1};
   ///@}
 
   /**
    * @name Conversion factor
    * @brief Conversion factor from * GeV<SUP>-2</SUP> to pb taken
    * from:
    * https://pdg.lbl.gov/2022/reviews/rpp2022-rev-phys-constants.pdf.
    */
   ///@{
   const double ConvFact = 0.3893793721e9;
   ///@}
 
   /**
    * @name Z-boson mass and width
    * @brief Value of the mass of the Z boson and its width in GeV
    * taken from:
    * https://pdg.lbl.gov/2023/listings/rpp2023-list-z-boson.pdf.
    */
   ///@{
   const double ZMass  = 91.1876;
   const double GammaZ = 2.4955;
   ///@}
 
   /**
    * @name W-boson mass and width
    * @brief Value of the mass of the W bosons and their width in GeV
    * taken from:
    * https://pdg.lbl.gov/2023/listings/rpp2023-list-w-boson.pdf.
    */
   ///@{
   const double WMass  = 80.377;
   const double GammaW = 2.085;
   ///@}
 
   /**
    * @name Proton mass
    * @brief Value of the mass of the proton in GeV taken from:
    * https://pdg.lbl.gov/2022/reviews/rpp2022-rev-phys-constants.pdf.
    */
   ///@{
   const double ProtonMass = 0.93827208816;
   ///@}
 
   /**
    * @name Weinberg angle
    * @brief Value of sin<SUP>2</SUP>&theta;<SUB>W</SUB> in the MSbar
    * scheme taken from:
    * https://pdg.lbl.gov/2022/reviews/rpp2022-rev-phys-constants.pdf.
    */
   ///@{
   const double Sin2ThetaW = 0.23121;
   ///@}
 
   /**
    * @name Fermi constant
    * @brief Value of G<SUB>F</SUB> in GeV<SUP>-2</SUP> taken from:
    * https://pdg.lbl.gov/2022/reviews/rpp2022-rev-phys-constants.pdf.
    */
   ///@{
   const double GFermi = 1.1663788e-5;
   ///@}
 
   /**
    * @name Fermi constant
    * @brief Value of G<SUB>F</SUB> in GeV<SUP>-2</SUP> taken from:
    * https://pdg.lbl.gov/2022/reviews/rpp2022-rev-phys-constants.pdf.
    */
   ///@{
   const double alphaem = 7.2973525693e-3;
   ///@}
 
   /**
    * @name CKM matrix elements
    * @brief Absolute value of the CMK matrix elements and their square
    * taken from:
    * http://pdg.lbl.gov/2018/reviews/rpp2018-rev-ckm-matrix.pdf.
    */
   ///@{
   const double Vud  = 0.97446;
   const double Vus  = 0.22452;
   const double Vub  = 0.00365;
   const double Vcd  = 0.22438;
   const double Vcs  = 0.97359;
   const double Vcb  = 0.04214;
   const double Vtd  = 0.00896;
   const double Vts  = 0.04133;
   const double Vtb  = 0.999105;
   const double Vud2 = Vud * Vud;
   const double Vus2 = Vus * Vus;
   const double Vub2 = Vub * Vub;
   const double Vcd2 = Vcd * Vcd;
   const double Vcs2 = Vcs * Vcs;
   const double Vcb2 = Vcb * Vcb;
   const double Vtd2 = Vtd * Vtd;
   const double Vts2 = Vts * Vts;
   const double Vtb2 = Vtb * Vtb;
   const std::vector<double> CKM  = {Vud,  Vus,  Vub,  Vcd,  Vcs,  Vcb,  Vtd,  Vts,  Vtb};
   const std::vector<double> CKM2 = {Vud2, Vus2, Vub2, Vcd2, Vcs2, Vcb2, Vtd2, Vts2, Vtb2};
   ///@}
   ///@}
 }

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