negative indexes allowed

[u/mrichter/AliRoot.git] / PDF / spdf / ctq4fn.F

C-----------------------------------------------------------------------
#include "pdf/pilot.h"
C============================================================================
C                CTEQ Parton Distribution Functions: Version 4.6
C                             June 21, 1996
C                   Modified: 10/17/96, 1/7/97, 1/15/97
C                             2/17/97, 2/21/97
C                   Last Modified on April 2, 1997
C
C   Ref[1]: "IMPROVED PARTON DISTRIBUTIONS FROM GLOBAL ANALYSIS OF RECENT DEEP
C         INELASTIC SCATTERING AND INCLUSIVE JET DATA"
C   By: H.L. Lai, J. Huston, S. Kuhlmann, F. Olness, J. Owens, D. Soper
C       W.K. Tung, H. Weerts
C       Phys. Rev. D55, 1280 (1997)
C
C   Ref[2]: "CHARM PRODUCTION AND PARTON DISTRIBUTIONS"
C   By: H.L. Lai and W.K. Tung
C       MSU-HEP-61222, CTEQ-622, e-Print Archive: hep-ph/9701256
C       to appear in Z. Phys.
C
C   This package contains 13 sets of CTEQ4 PDF's. Details are:
C ---------------------------------------------------------------------------
C  Iset   PDF        Description       Alpha_s(Mz)  Lam4  Lam5   Table_File
C ---------------------------------------------------------------------------
C Ref[1]
C   1    CTEQ4M   Standard MSbar scheme   0.116     298   202    cteq4m.tbl
C   2    CTEQ4D   Standard DIS scheme     0.116     298   202    cteq4d.tbl
C   3    CTEQ4L   Leading Order           0.132     236   181    cteq4l.tbl
C   4    CTEQ4A1  Alpha_s series          0.110     215   140    cteq4a1.tbl
C   5    CTEQ4A2  Alpha_s series          0.113     254   169    cteq4a2.tbl
C   6    CTEQ4A3            ( same as CTEQ4M )
C   7    CTEQ4A4  Alpha_s series          0.119     346   239    cteq4a4.tbl
C   8    CTEQ4A5  Alpha_s series          0.122     401   282    cteq4a5.tbl
C   9    CTEQ4HJ  High Jet                0.116     303   206    cteq4hj.tbl
C   10   CTEQ4LQ  Low Q0                  0.114     261   174    cteq4lq.tbl
C ---------------------------------------------------------------------------
C Ref[2]
C   11   CTEQ4HQ  Heavy Quark             0.116     298   202    cteq4hq.tbl
C   12   CTEQ4HQ1 Heavy Quark:Q0=1,Mc=1.3 0.116     298   202    cteq4hq1.tbl
C        (Improved version of CTEQ4HQ, recommended)
C   13   CTEQ4F3  Nf=3 FixedFlavorNumber  0.106     (Lam3=385)   cteq4f3.tbl
C   14   CTEQ4F4  Nf=4 FixedFlavorNumber  0.111     292   XXX    cteq4f4.tbl
C ---------------------------------------------------------------------------
C   
C   The available applied range is 10^-5 < x < 1 and 1.6 < Q < 10,000 (GeV) 
C   except CTEQ4LQ(4HQ1) for which Q starts at a lower value of 0.7(1.0) GeV.  
C   Lam5 (Lam4, Lam3) represents Lambda value (in MeV) for 5 (4,3) flavors. 
C   The matching alpha_s between 4 and 5 flavors takes place at Q=5.0 GeV,  
C   which is defined as the bottom quark mass, whenever it can be applied.
C
C   The Table_Files are assumed to be in the working directory.
C   
C   Before using the PDF, it is necessary to do the initialization by
C       Call SetCtq4(Iset) 
C   where Iset is the desired PDF specified in the above table.
C   
C   The function Ctq4Pdf (Iparton, X, Q)
C   returns the parton distribution inside the proton for parton [Iparton] 
C   at [X] Bjorken_X and scale [Q] (GeV) in PDF set [Iset].
C   Iparton  is the parton label (5, 4, 3, 2, 1, 0, -1, ......, -5)
C                            for (b, c, s, d, u, g, u_bar, ..., b_bar),
C      whereas CTEQ4F3 has, by definition, only 3 flavors and gluon;
C              CTEQ4F4 has only 4 flavors and gluon.
C   
C   For detailed information on the parameters used, e.q. quark masses, 
C   QCD Lambda, ... etc.,  see info lines at the beginning of the 
C   Table_Files.
C
C   These programs, as provided, are in double precision.  By removing the
C   "Implicit Double Precision" lines, they can also be run in single 
C   precision.
C   
C   If you have detailed questions concerning these CTEQ4 distributions, 
C   or if you find problems/bugs using this package, direct inquires to 
C   Hung-Liang Lai(Lai_H@pa.msu.edu) or Wu-Ki Tung(Tung@pa.msu.edu).
C   
C===========================================================================
#if defined(CERNLIB_SINGLE)
      Function Ctq4Fn (Iset, Iparton, X, Q)
#endif
#if defined(CERNLIB_DOUBLE)
      DOUBLE PRECISION FUNCTION Ctq4Fn (Iset, Iparton, X, Q)
#endif
#include "pdf/impdp.inc"
      Data Isetold, Isetmin, Isetmax / -987, 1, 10 /
      save

C             If data file not initialized, do so.
      If(Iset.ne.Isetold) then
         if(Iset.eq.1)  Call Ctq4RM  (Iset)
         if(Iset.eq.2)  Call Ctq4RD  (Iset)
         if(Iset.eq.3)  Call Ctq4RL  (Iset)
         if(Iset.eq.4)  Call Ctq4RA1 (Iset)
         if(Iset.eq.5)  Call Ctq4RA2 (Iset)
         if(Iset.eq.6)  Call Ctq4RM  (Iset)
         if(Iset.eq.7)  Call Ctq4RA4 (Iset)
         if(Iset.eq.8)  Call Ctq4RA5 (Iset)
         if(Iset.eq.9)  Call Ctq4RHJ (Iset)
         if(Iset.eq.10) Call Ctq4RlQ (Iset)
         if(Iset.eq.11) Call Ctq4RHQ (Iset)
         if(Iset.eq.12) Call Ctq4R_HQ1 (Iset)
         if(Iset.eq.13) Call Ctq4RF3 (Iset)
         if(Iset.eq.14) Call Ctq4RF4 (Iset)
         Isetold=Iset
      Endif
C
      Ctq4Fn = Ctq4PnX (Iparton, X, Q)
      if(Ctq4Fn.lt.0.D0)  Ctq4Fn = 0.D0
C
      Return
C                             ********************
      End