d3/d49/polfit_8F_source.html

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C                                                                            C

C       POLARIZED PARTON DISTRIBUTIONS (NLO and LO)                          C

C       FROM CERN-TH/71-97 AND HEP-PH 9711440                                C

C       D. de Florian, R. Sassot and O. Sampayo                              C

C                                                                            C

C       MODE: 1 SET1 NLO (MSbar)                                             C

C             2 SET2 NLO (MSbar)                                             C

C             3 SET3 NLO (MSbar)                                             C

C             4 SET1 LO                                                      C

C             5 SET2 LO                                                      C

C             6 SET3 LO                                                      C

C                                                                            C

C            Q2=Q^2                                                          C

C            DUV :    X * U VALENCE DISTRIBUTION                             C

C            DDV :    X * D VALENCE DISTRIBUTION                             C

C            DQBAR :  X * UBAR= X * DBAR DISTRIBUTION                        C

C            DSTR :   X * STR= X * STRBAR DISTRIBUTION                       C

C            DGLU :   X * GLUON DISTRIBUTION                                 C

C            G1P :    X * POLARIZED STRUCTURE FUNCTION (PROTON)              C

C            G1N :    X * POLARIZED STRUCTURE FUNCTION (NEUTRON)             C

C            G1D :    X * POLARIZED STRUCTURE FUNCTION(DEUTERON)             C

C                                                                            C

C       REMEMBER: ALWAYS X*DISTRIBUTION !!!                                  C

C        BEFORE CALLING THE SUBRUTINE `POLFIT` FOR THE FIRST TIME, THE       C

C       SUBROUTINE `INI` MUST BE CALLED (ONLY ONCE) TO READ THE GRIDS.       C

C              (CALL INI)                                                    C

C                                                                            C

C       RANGE OF VALIDITY OF THE INTERPOLATION:                              C

C                                   10**(-4)< X < 0.9                        C

C                                   1 < Q**2 < 5*10**4                       C

C                                                                            C

C       IN CASE OF PROBLEMS, DOUBTS, ETC, PLEASE REPORT TO                   C

C        Daniel.de.Florian@cern.ch                                           C

C                                                                            C

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      SUBROUTINE polfit(MODE,X,Q2,DUV,DDV,DQBAR,DSTR,DGLU)

************************

*HI    Speed optimized *

************************

       IMPLICIT NONE


      common/ xarray / xarray

      common/ grid / gu,gd,gl,gs,gg,gp,gn

      DOUBLE PRECISION xarray(102), gu(76,26), gd(76,26), gl(76,26),

     &     gs(76,26), gg(76,26), gp(76,26), gn(76,26)


      DOUBLE PRECISION xq(2),perinola,x3,x4,x5,x6,x7,x,q2

      DOUBLE PRECISION duv,ddv,dqbar,dstr,dglu

      INTEGER mode


      xq(1) = x

      xq(2) = q2

      x3=(1.d0-xq(1))**3.d0

      x4=(1.d0-xq(1))**4.d0

      x5=xq(1)**0.5d0

      x6=xq(1)**0.6d0

      x7=xq(1)**0.7d0

      duv = perinola(xq,gu) * x3* x6

      ddv = perinola(xq,gd) * x4 * x7

      dqbar = perinola(xq,gl) * x3 * x5

      dstr = perinola(xq,gs)  * x3 * x5

      dglu = perinola(xq,gg)  * x3 * x5

*HI      G1P = PERINOLA(XQ,GP)  * X3 * X5

*HI      G1N = PERINOLA(XQ,GN)  * X4 * X5

*HI      G1D=(G1P+G1N)*0.5D0*(1.D0-1.5D0*0.058D0)

      RETURN

      END