pyhistfu.f

    
C*********************************************************************  
    
      SUBROUTINE PYHISTFU(KF,X,Q2,XPQ,JBT)    
    
C			*******JBT specifies beam or target of the particle
C...Gives proton and pi+ parton structure functions according to a few  
C...different parametrizations. Note that what is coded is x times the  
C...probability distribution, i.e. xq(x,Q2) etc.    
      COMMON/HIPARNT/HIPR1(100),IHPR2(50),HINT1(100),IHNT2(50)
      SAVE  /HIPARNT/
      COMMON/HIJCRDN/YP(3,300),YT(3,300)
      SAVE  /HIJCRDN/
C			********COMMON BLOCK FROM HIJING
      COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) 
      SAVE  /LUDAT1/ 
      COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4)    
      SAVE  /LUDAT2/ 
      COMMON/PYHIPARS/MSTP(200),PARP(200),MSTI(200),PARI(200) 
      SAVE  /PYHIPARS/ 
      COMMON/PYHIINT1/MINT(400),VINT(400) 
      SAVE  /PYHIINT1/ 
      DIMENSION XPQ(-6:6),XQ(6),TX(6),TT(6),TS(6),NEHLQ(8,2),   
     &CEHLQ(6,6,2,8,2),CDO(3,6,5,2),COW(3,5,4,2)    

      SAVE XQ, TX, TT, TS, NEHLQ, CEHLQ, CDO, COW             ! Uzhi

    
C...The following data lines are coefficients needed in the 
C...Eichten, Hinchliffe, Lane, Quigg proton structure function  
C...parametrizations, see below.    
C...Powers of 1-x in different cases.   
      DATA NEHLQ/3,4,7,5,7,7,7,7,3,4,7,6,7,7,7,7/   
C...Expansion coefficients for up valence quark distribution.   
      DATA (((CEHLQ(IX,IT,NX,1,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 7.677E-01,-2.087E-01,-3.303E-01,-2.517E-02,-1.570E-02,-1.000E-04,    
     2-5.326E-01,-2.661E-01, 3.201E-01, 1.192E-01, 2.434E-02, 7.620E-03,    
     3 2.162E-01, 1.881E-01,-8.375E-02,-6.515E-02,-1.743E-02,-5.040E-03,    
     4-9.211E-02,-9.952E-02, 1.373E-02, 2.506E-02, 8.770E-03, 2.550E-03,    
     5 3.670E-02, 4.409E-02, 9.600E-04,-7.960E-03,-3.420E-03,-1.050E-03,    
     6-1.549E-02,-2.026E-02,-3.060E-03, 2.220E-03, 1.240E-03, 4.100E-04,    
     1 2.395E-01, 2.905E-01, 9.778E-02, 2.149E-02, 3.440E-03, 5.000E-04,    
     2 1.751E-02,-6.090E-03,-2.687E-02,-1.916E-02,-7.970E-03,-2.750E-03,    
     3-5.760E-03,-5.040E-03, 1.080E-03, 2.490E-03, 1.530E-03, 7.500E-04,    
     4 1.740E-03, 1.960E-03, 3.000E-04,-3.400E-04,-2.900E-04,-1.800E-04,    
     5-5.300E-04,-6.400E-04,-1.700E-04, 4.000E-05, 6.000E-05, 4.000E-05,    
     6 1.700E-04, 2.200E-04, 8.000E-05, 1.000E-05,-1.000E-05,-1.000E-05/    
      DATA (((CEHLQ(IX,IT,NX,1,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 7.237E-01,-2.189E-01,-2.995E-01,-1.909E-02,-1.477E-02, 2.500E-04,    
     2-5.314E-01,-2.425E-01, 3.283E-01, 1.119E-01, 2.223E-02, 7.070E-03,    
     3 2.289E-01, 1.890E-01,-9.859E-02,-6.900E-02,-1.747E-02,-5.080E-03,    
     4-1.041E-01,-1.084E-01, 2.108E-02, 2.975E-02, 9.830E-03, 2.830E-03,    
     5 4.394E-02, 5.116E-02,-1.410E-03,-1.055E-02,-4.230E-03,-1.270E-03,    
     6-1.991E-02,-2.539E-02,-2.780E-03, 3.430E-03, 1.720E-03, 5.500E-04,    
     1 2.410E-01, 2.884E-01, 9.369E-02, 1.900E-02, 2.530E-03, 2.400E-04,    
     2 1.765E-02,-9.220E-03,-3.037E-02,-2.085E-02,-8.440E-03,-2.810E-03,    
     3-6.450E-03,-5.260E-03, 1.720E-03, 3.110E-03, 1.830E-03, 8.700E-04,    
     4 2.120E-03, 2.320E-03, 2.600E-04,-4.900E-04,-3.900E-04,-2.300E-04,    
     5-6.900E-04,-8.200E-04,-2.000E-04, 7.000E-05, 9.000E-05, 6.000E-05,    
     6 2.400E-04, 3.100E-04, 1.100E-04, 0.000E+00,-2.000E-05,-2.000E-05/    
C...Expansion coefficients for down valence quark distribution. 
      DATA (((CEHLQ(IX,IT,NX,2,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 3.813E-01,-8.090E-02,-1.634E-01,-2.185E-02,-8.430E-03,-6.200E-04,    
     2-2.948E-01,-1.435E-01, 1.665E-01, 6.638E-02, 1.473E-02, 4.080E-03,    
     3 1.252E-01, 1.042E-01,-4.722E-02,-3.683E-02,-1.038E-02,-2.860E-03,    
     4-5.478E-02,-5.678E-02, 8.900E-03, 1.484E-02, 5.340E-03, 1.520E-03,    
     5 2.220E-02, 2.567E-02,-3.000E-05,-4.970E-03,-2.160E-03,-6.500E-04,    
     6-9.530E-03,-1.204E-02,-1.510E-03, 1.510E-03, 8.300E-04, 2.700E-04,    
     1 1.261E-01, 1.354E-01, 3.958E-02, 8.240E-03, 1.660E-03, 4.500E-04,    
     2 3.890E-03,-1.159E-02,-1.625E-02,-9.610E-03,-3.710E-03,-1.260E-03,    
     3-1.910E-03,-5.600E-04, 1.590E-03, 1.590E-03, 8.400E-04, 3.900E-04,    
     4 6.400E-04, 4.900E-04,-1.500E-04,-2.900E-04,-1.800E-04,-1.000E-04,    
     5-2.000E-04,-1.900E-04, 0.000E+00, 6.000E-05, 4.000E-05, 3.000E-05,    
     6 7.000E-05, 8.000E-05, 2.000E-05,-1.000E-05,-1.000E-05,-1.000E-05/    
      DATA (((CEHLQ(IX,IT,NX,2,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 3.578E-01,-8.622E-02,-1.480E-01,-1.840E-02,-7.820E-03,-4.500E-04,    
     2-2.925E-01,-1.304E-01, 1.696E-01, 6.243E-02, 1.353E-02, 3.750E-03,    
     3 1.318E-01, 1.041E-01,-5.486E-02,-3.872E-02,-1.038E-02,-2.850E-03,    
     4-6.162E-02,-6.143E-02, 1.303E-02, 1.740E-02, 5.940E-03, 1.670E-03,    
     5 2.643E-02, 2.957E-02,-1.490E-03,-6.450E-03,-2.630E-03,-7.700E-04,    
     6-1.218E-02,-1.497E-02,-1.260E-03, 2.240E-03, 1.120E-03, 3.500E-04,    
     1 1.263E-01, 1.334E-01, 3.732E-02, 7.070E-03, 1.260E-03, 3.400E-04,    
     2 3.660E-03,-1.357E-02,-1.795E-02,-1.031E-02,-3.880E-03,-1.280E-03,    
     3-2.100E-03,-3.600E-04, 2.050E-03, 1.920E-03, 9.800E-04, 4.400E-04,    
     4 7.700E-04, 5.400E-04,-2.400E-04,-3.900E-04,-2.400E-04,-1.300E-04,    
     5-2.600E-04,-2.300E-04, 2.000E-05, 9.000E-05, 6.000E-05, 4.000E-05,    
     6 9.000E-05, 1.000E-04, 2.000E-05,-2.000E-05,-2.000E-05,-1.000E-05/    
C...Expansion coefficients for up and down sea quark distributions. 
      DATA (((CEHLQ(IX,IT,NX,3,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 6.870E-02,-6.861E-02, 2.973E-02,-5.400E-03, 3.780E-03,-9.700E-04,    
     2-1.802E-02, 1.400E-04, 6.490E-03,-8.540E-03, 1.220E-03,-1.750E-03,    
     3-4.650E-03, 1.480E-03,-5.930E-03, 6.000E-04,-1.030E-03,-8.000E-05,    
     4 6.440E-03, 2.570E-03, 2.830E-03, 1.150E-03, 7.100E-04, 3.300E-04,    
     5-3.930E-03,-2.540E-03,-1.160E-03,-7.700E-04,-3.600E-04,-1.900E-04,    
     6 2.340E-03, 1.930E-03, 5.300E-04, 3.700E-04, 1.600E-04, 9.000E-05,    
     1 1.014E+00,-1.106E+00, 3.374E-01,-7.444E-02, 8.850E-03,-8.700E-04,    
     2 9.233E-01,-1.285E+00, 4.475E-01,-9.786E-02, 1.419E-02,-1.120E-03,    
     3 4.888E-02,-1.271E-01, 8.606E-02,-2.608E-02, 4.780E-03,-6.000E-04,    
     4-2.691E-02, 4.887E-02,-1.771E-02, 1.620E-03, 2.500E-04,-6.000E-05,    
     5 7.040E-03,-1.113E-02, 1.590E-03, 7.000E-04,-2.000E-04, 0.000E+00,    
     6-1.710E-03, 2.290E-03, 3.800E-04,-3.500E-04, 4.000E-05, 1.000E-05/    
      DATA (((CEHLQ(IX,IT,NX,3,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 1.008E-01,-7.100E-02, 1.973E-02,-5.710E-03, 2.930E-03,-9.900E-04,    
     2-5.271E-02,-1.823E-02, 1.792E-02,-6.580E-03, 1.750E-03,-1.550E-03,    
     3 1.220E-02, 1.763E-02,-8.690E-03,-8.800E-04,-1.160E-03,-2.100E-04,    
     4-1.190E-03,-7.180E-03, 2.360E-03, 1.890E-03, 7.700E-04, 4.100E-04,    
     5-9.100E-04, 2.040E-03,-3.100E-04,-1.050E-03,-4.000E-04,-2.400E-04,    
     6 1.190E-03,-1.700E-04,-2.000E-04, 4.200E-04, 1.700E-04, 1.000E-04,    
     1 1.081E+00,-1.189E+00, 3.868E-01,-8.617E-02, 1.115E-02,-1.180E-03,    
     2 9.917E-01,-1.396E+00, 4.998E-01,-1.159E-01, 1.674E-02,-1.720E-03,    
     3 5.099E-02,-1.338E-01, 9.173E-02,-2.885E-02, 5.890E-03,-6.500E-04,    
     4-3.178E-02, 5.703E-02,-2.070E-02, 2.440E-03, 1.100E-04,-9.000E-05,    
     5 8.970E-03,-1.392E-02, 2.050E-03, 6.500E-04,-2.300E-04, 2.000E-05,    
     6-2.340E-03, 3.010E-03, 5.000E-04,-3.900E-04, 6.000E-05, 1.000E-05/    
C...Expansion coefficients for gluon distribution.  
      DATA (((CEHLQ(IX,IT,NX,4,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 9.482E-01,-9.578E-01, 1.009E-01,-1.051E-01, 3.456E-02,-3.054E-02,    
     2-9.627E-01, 5.379E-01, 3.368E-01,-9.525E-02, 1.488E-02,-2.051E-02,    
     3 4.300E-01,-8.306E-02,-3.372E-01, 4.902E-02,-9.160E-03, 1.041E-02,    
     4-1.925E-01,-1.790E-02, 2.183E-01, 7.490E-03, 4.140E-03,-1.860E-03,    
     5 8.183E-02, 1.926E-02,-1.072E-01,-1.944E-02,-2.770E-03,-5.200E-04,    
     6-3.884E-02,-1.234E-02, 5.410E-02, 1.879E-02, 3.350E-03, 1.040E-03,    
     1 2.948E+01,-3.902E+01, 1.464E+01,-3.335E+00, 5.054E-01,-5.915E-02,    
     2 2.559E+01,-3.955E+01, 1.661E+01,-4.299E+00, 6.904E-01,-8.243E-02,    
     3-1.663E+00, 1.176E+00, 1.118E+00,-7.099E-01, 1.948E-01,-2.404E-02,    
     4-2.168E-01, 8.170E-01,-7.169E-01, 1.851E-01,-1.924E-02,-3.250E-03,    
     5 2.088E-01,-4.355E-01, 2.239E-01,-2.446E-02,-3.620E-03, 1.910E-03,    
     6-9.097E-02, 1.601E-01,-5.681E-02,-2.500E-03, 2.580E-03,-4.700E-04/    
      DATA (((CEHLQ(IX,IT,NX,4,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 2.367E+00, 4.453E-01, 3.660E-01, 9.467E-02, 1.341E-01, 1.661E-02,    
     2-3.170E+00,-1.795E+00, 3.313E-02,-2.874E-01,-9.827E-02,-7.119E-02,    
     3 1.823E+00, 1.457E+00,-2.465E-01, 3.739E-02, 6.090E-03, 1.814E-02,    
     4-1.033E+00,-9.827E-01, 2.136E-01, 1.169E-01, 5.001E-02, 1.684E-02,    
     5 5.133E-01, 5.259E-01,-1.173E-01,-1.139E-01,-4.988E-02,-2.021E-02,    
     6-2.881E-01,-3.145E-01, 5.667E-02, 9.161E-02, 4.568E-02, 1.951E-02,    
     1 3.036E+01,-4.062E+01, 1.578E+01,-3.699E+00, 6.020E-01,-7.031E-02,    
     2 2.700E+01,-4.167E+01, 1.770E+01,-4.804E+00, 7.862E-01,-1.060E-01,    
     3-1.909E+00, 1.357E+00, 1.127E+00,-7.181E-01, 2.232E-01,-2.481E-02,    
     4-2.488E-01, 9.781E-01,-8.127E-01, 2.094E-01,-2.997E-02,-4.710E-03,    
     5 2.506E-01,-5.427E-01, 2.672E-01,-3.103E-02,-1.800E-03, 2.870E-03,    
     6-1.128E-01, 2.087E-01,-6.972E-02,-2.480E-03, 2.630E-03,-8.400E-04/    
C...Expansion coefficients for strange sea quark distribution.  
      DATA (((CEHLQ(IX,IT,NX,5,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 4.968E-02,-4.173E-02, 2.102E-02,-3.270E-03, 3.240E-03,-6.700E-04,    
     2-6.150E-03,-1.294E-02, 6.740E-03,-6.890E-03, 9.000E-04,-1.510E-03,    
     3-8.580E-03, 5.050E-03,-4.900E-03,-1.600E-04,-9.400E-04,-1.500E-04,    
     4 7.840E-03, 1.510E-03, 2.220E-03, 1.400E-03, 7.000E-04, 3.500E-04,    
     5-4.410E-03,-2.220E-03,-8.900E-04,-8.500E-04,-3.600E-04,-2.000E-04,    
     6 2.520E-03, 1.840E-03, 4.100E-04, 3.900E-04, 1.600E-04, 9.000E-05,    
     1 9.235E-01,-1.085E+00, 3.464E-01,-7.210E-02, 9.140E-03,-9.100E-04,    
     2 9.315E-01,-1.274E+00, 4.512E-01,-9.775E-02, 1.380E-02,-1.310E-03,    
     3 4.739E-02,-1.296E-01, 8.482E-02,-2.642E-02, 4.760E-03,-5.700E-04,    
     4-2.653E-02, 4.953E-02,-1.735E-02, 1.750E-03, 2.800E-04,-6.000E-05,    
     5 6.940E-03,-1.132E-02, 1.480E-03, 6.500E-04,-2.100E-04, 0.000E+00,    
     6-1.680E-03, 2.340E-03, 4.200E-04,-3.400E-04, 5.000E-05, 1.000E-05/    
      DATA (((CEHLQ(IX,IT,NX,5,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 6.478E-02,-4.537E-02, 1.643E-02,-3.490E-03, 2.710E-03,-6.700E-04,    
     2-2.223E-02,-2.126E-02, 1.247E-02,-6.290E-03, 1.120E-03,-1.440E-03,    
     3-1.340E-03, 1.362E-02,-6.130E-03,-7.900E-04,-9.000E-04,-2.000E-04,    
     4 5.080E-03,-3.610E-03, 1.700E-03, 1.830E-03, 6.800E-04, 4.000E-04,    
     5-3.580E-03, 6.000E-05,-2.600E-04,-1.050E-03,-3.800E-04,-2.300E-04,    
     6 2.420E-03, 9.300E-04,-1.000E-04, 4.500E-04, 1.700E-04, 1.100E-04,    
     1 9.868E-01,-1.171E+00, 3.940E-01,-8.459E-02, 1.124E-02,-1.250E-03,    
     2 1.001E+00,-1.383E+00, 5.044E-01,-1.152E-01, 1.658E-02,-1.830E-03,    
     3 4.928E-02,-1.368E-01, 9.021E-02,-2.935E-02, 5.800E-03,-6.600E-04,    
     4-3.133E-02, 5.785E-02,-2.023E-02, 2.630E-03, 1.600E-04,-8.000E-05,    
     5 8.840E-03,-1.416E-02, 1.900E-03, 5.800E-04,-2.500E-04, 1.000E-05,    
     6-2.300E-03, 3.080E-03, 5.500E-04,-3.700E-04, 7.000E-05, 1.000E-05/    
C...Expansion coefficients for charm sea quark distribution.    
      DATA (((CEHLQ(IX,IT,NX,6,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 9.270E-03,-1.817E-02, 9.590E-03,-6.390E-03, 1.690E-03,-1.540E-03,    
     2 5.710E-03,-1.188E-02, 6.090E-03,-4.650E-03, 1.240E-03,-1.310E-03,    
     3-3.960E-03, 7.100E-03,-3.590E-03, 1.840E-03,-3.900E-04, 3.400E-04,    
     4 1.120E-03,-1.960E-03, 1.120E-03,-4.800E-04, 1.000E-04,-4.000E-05,    
     5 4.000E-05,-3.000E-05,-1.800E-04, 9.000E-05,-5.000E-05,-2.000E-05,    
     6-4.200E-04, 7.300E-04,-1.600E-04, 5.000E-05, 5.000E-05, 5.000E-05,    
     1 8.098E-01,-1.042E+00, 3.398E-01,-6.824E-02, 8.760E-03,-9.000E-04,    
     2 8.961E-01,-1.217E+00, 4.339E-01,-9.287E-02, 1.304E-02,-1.290E-03,    
     3 3.058E-02,-1.040E-01, 7.604E-02,-2.415E-02, 4.600E-03,-5.000E-04,    
     4-2.451E-02, 4.432E-02,-1.651E-02, 1.430E-03, 1.200E-04,-1.000E-04,    
     5 1.122E-02,-1.457E-02, 2.680E-03, 5.800E-04,-1.200E-04, 3.000E-05,    
     6-7.730E-03, 7.330E-03,-7.600E-04,-2.400E-04, 1.000E-05, 0.000E+00/    
      DATA (((CEHLQ(IX,IT,NX,6,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 9.980E-03,-1.945E-02, 1.055E-02,-6.870E-03, 1.860E-03,-1.560E-03,    
     2 5.700E-03,-1.203E-02, 6.250E-03,-4.860E-03, 1.310E-03,-1.370E-03,    
     3-4.490E-03, 7.990E-03,-4.170E-03, 2.050E-03,-4.400E-04, 3.300E-04,    
     4 1.470E-03,-2.480E-03, 1.460E-03,-5.700E-04, 1.200E-04,-1.000E-05,    
     5-9.000E-05, 1.500E-04,-3.200E-04, 1.200E-04,-6.000E-05,-4.000E-05,    
     6-4.200E-04, 7.600E-04,-1.400E-04, 4.000E-05, 7.000E-05, 5.000E-05,    
     1 8.698E-01,-1.131E+00, 3.836E-01,-8.111E-02, 1.048E-02,-1.300E-03,    
     2 9.626E-01,-1.321E+00, 4.854E-01,-1.091E-01, 1.583E-02,-1.700E-03,    
     3 3.057E-02,-1.088E-01, 8.022E-02,-2.676E-02, 5.590E-03,-5.600E-04,    
     4-2.845E-02, 5.164E-02,-1.918E-02, 2.210E-03,-4.000E-05,-1.500E-04,    
     5 1.311E-02,-1.751E-02, 3.310E-03, 5.100E-04,-1.200E-04, 5.000E-05,    
     6-8.590E-03, 8.380E-03,-9.200E-04,-2.600E-04, 1.000E-05,-1.000E-05/    
C...Expansion coefficients for bottom sea quark distribution.   
      DATA (((CEHLQ(IX,IT,NX,7,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 9.010E-03,-1.401E-02, 7.150E-03,-4.130E-03, 1.260E-03,-1.040E-03,    
     2 6.280E-03,-9.320E-03, 4.780E-03,-2.890E-03, 9.100E-04,-8.200E-04,    
     3-2.930E-03, 4.090E-03,-1.890E-03, 7.600E-04,-2.300E-04, 1.400E-04,    
     4 3.900E-04,-1.200E-03, 4.400E-04,-2.500E-04, 2.000E-05,-2.000E-05,    
     5 2.600E-04, 1.400E-04,-8.000E-05, 1.000E-04, 1.000E-05, 1.000E-05,    
     6-2.600E-04, 3.200E-04, 1.000E-05,-1.000E-05, 1.000E-05,-1.000E-05,    
     1 8.029E-01,-1.075E+00, 3.792E-01,-7.843E-02, 1.007E-02,-1.090E-03,    
     2 7.903E-01,-1.099E+00, 4.153E-01,-9.301E-02, 1.317E-02,-1.410E-03,    
     3-1.704E-02,-1.130E-02, 2.882E-02,-1.341E-02, 3.040E-03,-3.600E-04,    
     4-7.200E-04, 7.230E-03,-5.160E-03, 1.080E-03,-5.000E-05,-4.000E-05,    
     5 3.050E-03,-4.610E-03, 1.660E-03,-1.300E-04,-1.000E-05, 1.000E-05,    
     6-4.360E-03, 5.230E-03,-1.610E-03, 2.000E-04,-2.000E-05, 0.000E+00/    
      DATA (((CEHLQ(IX,IT,NX,7,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 8.980E-03,-1.459E-02, 7.510E-03,-4.410E-03, 1.310E-03,-1.070E-03,    
     2 5.970E-03,-9.440E-03, 4.800E-03,-3.020E-03, 9.100E-04,-8.500E-04,    
     3-3.050E-03, 4.440E-03,-2.100E-03, 8.500E-04,-2.400E-04, 1.400E-04,    
     4 5.300E-04,-1.300E-03, 5.600E-04,-2.700E-04, 3.000E-05,-2.000E-05,    
     5 2.000E-04, 1.400E-04,-1.100E-04, 1.000E-04, 0.000E+00, 0.000E+00,    
     6-2.600E-04, 3.200E-04, 0.000E+00,-3.000E-05, 1.000E-05,-1.000E-05,    
     1 8.672E-01,-1.174E+00, 4.265E-01,-9.252E-02, 1.244E-02,-1.460E-03,    
     2 8.500E-01,-1.194E+00, 4.630E-01,-1.083E-01, 1.614E-02,-1.830E-03,    
     3-2.241E-02,-5.630E-03, 2.815E-02,-1.425E-02, 3.520E-03,-4.300E-04,    
     4-7.300E-04, 8.030E-03,-5.780E-03, 1.380E-03,-1.300E-04,-4.000E-05,    
     5 3.460E-03,-5.380E-03, 1.960E-03,-2.100E-04, 1.000E-05, 1.000E-05,    
     6-4.850E-03, 5.950E-03,-1.890E-03, 2.600E-04,-3.000E-05, 0.000E+00/    
C...Expansion coefficients for top sea quark distribution.  
      DATA (((CEHLQ(IX,IT,NX,8,1),IX=1,6),IT=1,6),NX=1,2)/  
     1 4.410E-03,-7.480E-03, 3.770E-03,-2.580E-03, 7.300E-04,-7.100E-04,    
     2 3.840E-03,-6.050E-03, 3.030E-03,-2.030E-03, 5.800E-04,-5.900E-04,    
     3-8.800E-04, 1.660E-03,-7.500E-04, 4.700E-04,-1.000E-04, 1.000E-04,    
     4-8.000E-05,-1.500E-04, 1.200E-04,-9.000E-05, 3.000E-05, 0.000E+00,    
     5 1.300E-04,-2.200E-04,-2.000E-05,-2.000E-05,-2.000E-05,-2.000E-05,    
     6-7.000E-05, 1.900E-04,-4.000E-05, 2.000E-05, 0.000E+00, 0.000E+00,    
     1 6.623E-01,-9.248E-01, 3.519E-01,-7.930E-02, 1.110E-02,-1.180E-03,    
     2 6.380E-01,-9.062E-01, 3.582E-01,-8.479E-02, 1.265E-02,-1.390E-03,    
     3-2.581E-02, 2.125E-02, 4.190E-03,-4.980E-03, 1.490E-03,-2.100E-04,    
     4 7.100E-04, 5.300E-04,-1.270E-03, 3.900E-04,-5.000E-05,-1.000E-05,    
     5 3.850E-03,-5.060E-03, 1.860E-03,-3.500E-04, 4.000E-05, 0.000E+00,    
     6-3.530E-03, 4.460E-03,-1.500E-03, 2.700E-04,-3.000E-05, 0.000E+00/    
      DATA (((CEHLQ(IX,IT,NX,8,2),IX=1,6),IT=1,6),NX=1,2)/  
     1 4.260E-03,-7.530E-03, 3.830E-03,-2.680E-03, 7.600E-04,-7.300E-04,    
     2 3.640E-03,-6.050E-03, 3.030E-03,-2.090E-03, 5.900E-04,-6.000E-04,    
     3-9.200E-04, 1.710E-03,-8.200E-04, 5.000E-04,-1.200E-04, 1.000E-04,    
     4-5.000E-05,-1.600E-04, 1.300E-04,-9.000E-05, 3.000E-05, 0.000E+00,    
     5 1.300E-04,-2.100E-04,-1.000E-05,-2.000E-05,-2.000E-05,-1.000E-05,    
     6-8.000E-05, 1.800E-04,-5.000E-05, 2.000E-05, 0.000E+00, 0.000E+00,    
     1 7.146E-01,-1.007E+00, 3.932E-01,-9.246E-02, 1.366E-02,-1.540E-03,    
     2 6.856E-01,-9.828E-01, 3.977E-01,-9.795E-02, 1.540E-02,-1.790E-03,    
     3-3.053E-02, 2.758E-02, 2.150E-03,-4.880E-03, 1.640E-03,-2.500E-04,    
     4 9.200E-04, 4.200E-04,-1.340E-03, 4.600E-04,-8.000E-05,-1.000E-05,    
     5 4.230E-03,-5.660E-03, 2.140E-03,-4.300E-04, 6.000E-05, 0.000E+00,    
     6-3.890E-03, 5.000E-03,-1.740E-03, 3.300E-04,-4.000E-05, 0.000E+00/    
    
C...The following data lines are coefficients needed in the 
C...Duke, Owens proton structure function parametrizations, see below.  
C...Expansion coefficients for (up+down) valence quark distribution.    
      DATA ((CDO(IP,IS,1,1),IS=1,6),IP=1,3)/    
     1 4.190E-01, 3.460E+00, 4.400E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2 4.000E-03, 7.240E-01,-4.860E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     3-7.000E-03,-6.600E-02, 1.330E+00, 0.000E+00, 0.000E+00, 0.000E+00/    
      DATA ((CDO(IP,IS,1,2),IS=1,6),IP=1,3)/    
     1 3.740E-01, 3.330E+00, 6.030E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2 1.400E-02, 7.530E-01,-6.220E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     3 0.000E+00,-7.600E-02, 1.560E+00, 0.000E+00, 0.000E+00, 0.000E+00/    
C...Expansion coefficients for down valence quark distribution. 
      DATA ((CDO(IP,IS,2,1),IS=1,6),IP=1,3)/    
     1 7.630E-01, 4.000E+00, 0.000E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2-2.370E-01, 6.270E-01,-4.210E-01, 0.000E+00, 0.000E+00, 0.000E+00,    
     3 2.600E-02,-1.900E-02, 3.300E-02, 0.000E+00, 0.000E+00, 0.000E+00/    
      DATA ((CDO(IP,IS,2,2),IS=1,6),IP=1,3)/    
     1 7.610E-01, 3.830E+00, 0.000E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2-2.320E-01, 6.270E-01,-4.180E-01, 0.000E+00, 0.000E+00, 0.000E+00,    
     3 2.300E-02,-1.900E-02, 3.600E-02, 0.000E+00, 0.000E+00, 0.000E+00/    
C...Expansion coefficients for (up+down+strange) sea quark distribution.    
      DATA ((CDO(IP,IS,3,1),IS=1,6),IP=1,3)/    
     1 1.265E+00, 0.000E+00, 8.050E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2-1.132E+00,-3.720E-01, 1.590E+00, 6.310E+00,-1.050E+01, 1.470E+01,    
     3 2.930E-01,-2.900E-02,-1.530E-01,-2.730E-01,-3.170E+00, 9.800E+00/    
      DATA ((CDO(IP,IS,3,2),IS=1,6),IP=1,3)/    
     1 1.670E+00, 0.000E+00, 9.150E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2-1.920E+00,-2.730E-01, 5.300E-01, 1.570E+01,-1.010E+02, 2.230E+02,    
     3 5.820E-01,-1.640E-01,-7.630E-01,-2.830E+00, 4.470E+01,-1.170E+02/    
C...Expansion coefficients for charm sea quark distribution.    
      DATA ((CDO(IP,IS,4,1),IS=1,6),IP=1,3)/    
     1 0.000E+00,-3.600E-02, 6.350E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2 1.350E-01,-2.220E-01, 3.260E+00,-3.030E+00, 1.740E+01,-1.790E+01,    
     3-7.500E-02,-5.800E-02,-9.090E-01, 1.500E+00,-1.130E+01, 1.560E+01/    
       DATA ((CDO(IP,IS,4,2),IS=1,6),IP=1,3)/   
     1 0.000E+00,-1.200E-01, 3.510E+00, 0.000E+00, 0.000E+00, 0.000E+00,    
     2 6.700E-02,-2.330E-01, 3.660E+00,-4.740E-01, 9.500E+00,-1.660E+01,    
     3-3.100E-02,-2.300E-02,-4.530E-01, 3.580E-01,-5.430E+00, 1.550E+01/    
C...Expansion coefficients for gluon distribution.  
      DATA ((CDO(IP,IS,5,1),IS=1,6),IP=1,3)/    
     1 1.560E+00, 0.000E+00, 6.000E+00, 9.000E+00, 0.000E+00, 0.000E+00,    
     2-1.710E+00,-9.490E-01, 1.440E+00,-7.190E+00,-1.650E+01, 1.530E+01,    
     3 6.380E-01, 3.250E-01,-1.050E+00, 2.550E-01, 1.090E+01,-1.010E+01/    
      DATA ((CDO(IP,IS,5,2),IS=1,6),IP=1,3)/    
     1 8.790E-01, 0.000E+00, 4.000E+00, 9.000E+00, 0.000E+00, 0.000E+00,    
     2-9.710E-01,-1.160E+00, 1.230E+00,-5.640E+00,-7.540E+00,-5.960E-01,    
     3 4.340E-01, 4.760E-01,-2.540E-01,-8.170E-01, 5.500E+00, 1.260E-01/    
    
C...The following data lines are coefficients needed in the 
C...Owens pion structure function parametrizations, see below.  
C...Expansion coefficients for up and down valence quark distributions. 
      DATA ((COW(IP,IS,1,1),IS=1,5),IP=1,3)/    
     1  4.0000E-01,  7.0000E-01,  0.0000E+00,  0.0000E+00,  0.0000E+00, 
     2 -6.2120E-02,  6.4780E-01,  0.0000E+00,  0.0000E+00,  0.0000E+00, 
     3 -7.1090E-03,  1.3350E-02,  0.0000E+00,  0.0000E+00,  0.0000E+00/ 
      DATA ((COW(IP,IS,1,2),IS=1,5),IP=1,3)/    
     1  4.0000E-01,  6.2800E-01,  0.0000E+00,  0.0000E+00,  0.0000E+00, 
     2 -5.9090E-02,  6.4360E-01,  0.0000E+00,  0.0000E+00,  0.0000E+00, 
     3 -6.5240E-03,  1.4510E-02,  0.0000E+00,  0.0000E+00,  0.0000E+00/ 
C...Expansion coefficients for gluon distribution.  
      DATA ((COW(IP,IS,2,1),IS=1,5),IP=1,3)/    
     1  8.8800E-01,  0.0000E+00,  3.1100E+00,  6.0000E+00,  0.0000E+00, 
     2 -1.8020E+00, -1.5760E+00, -1.3170E-01,  2.8010E+00, -1.7280E+01, 
     3  1.8120E+00,  1.2000E+00,  5.0680E-01, -1.2160E+01,  2.0490E+01/ 
      DATA ((COW(IP,IS,2,2),IS=1,5),IP=1,3)/    
     1  7.9400E-01,  0.0000E+00,  2.8900E+00,  6.0000E+00,  0.0000E+00, 
     2 -9.1440E-01, -1.2370E+00,  5.9660E-01, -3.6710E+00, -8.1910E+00, 
     3  5.9660E-01,  6.5820E-01, -2.5500E-01, -2.3040E+00,  7.7580E+00/ 
C...Expansion coefficients for (up+down+strange) quark sea distribution.    
      DATA ((COW(IP,IS,3,1),IS=1,5),IP=1,3)/    
     1  9.0000E-01,  0.0000E+00,  5.0000E+00,  0.0000E+00,  0.0000E+00, 
     2 -2.4280E-01, -2.1200E-01,  8.6730E-01,  1.2660E+00,  2.3820E+00, 
     3  1.3860E-01,  3.6710E-03,  4.7470E-02, -2.2150E+00,  3.4820E-01/ 
      DATA ((COW(IP,IS,3,2),IS=1,5),IP=1,3)/    
     1  9.0000E-01,  0.0000E+00,  5.0000E+00,  0.0000E+00,  0.0000E+00, 
     2 -1.4170E-01, -1.6970E-01, -2.4740E+00, -2.5340E+00,  5.6210E-01, 
     3 -1.7400E-01, -9.6230E-02,  1.5750E+00,  1.3780E+00, -2.7010E-01/ 
C...Expansion coefficients for charm quark sea distribution.    
      DATA ((COW(IP,IS,4,1),IS=1,5),IP=1,3)/    
     1  0.0000E+00, -2.2120E-02,  2.8940E+00,  0.0000E+00,  0.0000E+00, 
     2  7.9280E-02, -3.7850E-01,  9.4330E+00,  5.2480E+00,  8.3880E+00, 
     3 -6.1340E-02, -1.0880E-01, -1.0852E+01, -7.1870E+00, -1.1610E+01/ 
      DATA ((COW(IP,IS,4,2),IS=1,5),IP=1,3)/    
     1  0.0000E+00, -8.8200E-02,  1.9240E+00,  0.0000E+00,  0.0000E+00, 
     2  6.2290E-02, -2.8920E-01,  2.4240E-01, -4.4630E+00, -8.3670E-01, 
     3 -4.0990E-02, -1.0820E-01,  2.0360E+00,  5.2090E+00, -4.8400E-02/ 
    
C...Euler's beta function, requires ordinary Gamma function 
      EULBET(X,Y)=PYHIGAMM(X)*PYHIGAMM(Y)/PYHIGAMM(X+Y)   
    
C...Reset structure functions, check x and hadron flavour.  
      ALAM=0.   
      DO 100 KFL=-6,6   
  100 XPQ(KFL)=0.   
      IF(X.LT.0..OR.X.GT.1.) THEN   
        WRITE(MSTU(11),1000) X  
        RETURN  
      ENDIF 
      KFA=IABS(KF)  
      IF(KFA.NE.211.AND.KFA.NE.2212.AND.KFA.NE.2112) THEN   
        WRITE(MSTU(11),1100) KF 
        RETURN  
      ENDIF 
    
C...Call user-supplied structure function. Select proton/neutron/pion.  
      IF(MSTP(51).EQ.0.OR.MSTP(52).GE.2) THEN   
        KFE=KFA 
        IF(KFA.EQ.2112) KFE=2212    
        CALL PYHISTFE(KFE,X,Q2,XPQ)   
        GOTO 230    
      ENDIF 
      IF(KFA.EQ.211) GOTO 200   
    
      IF(MSTP(51).EQ.1.OR.MSTP(51).EQ.2) THEN   
C...Proton structure functions from Eichten, Hinchliffe, Lane, Quigg.   
C...Allowed variable range: 5 GeV2 < Q2 < 1E8 GeV2; 1E-4 < x < 1    
    
C...Determine set, Lamdba and x and t expansion variables.  
        NSET=MSTP(51)   
        IF(NSET.EQ.1) ALAM=0.2  
        IF(NSET.EQ.2) ALAM=0.29 
        TMIN=LOG(5./ALAM**2)    
        TMAX=LOG(1E8/ALAM**2)   
        IF(MSTP(52).EQ.0) THEN  
          T=TMIN    
        ELSE    
          T=LOG(Q2/ALAM**2) 
        ENDIF   
        VT=MAX(-1.,MIN(1.,(2.*T-TMAX-TMIN)/(TMAX-TMIN)))    
        NX=1    
        IF(X.LE.0.1) NX=2   
        IF(NX.EQ.1) VX=(2.*X-1.1)/0.9   
        IF(NX.EQ.2) VX=MAX(-1.,(2.*LOG(X)+11.51293)/6.90776)    
        CXS=1.  
        IF(X.LT.1E-4.AND.ABS(PARP(51)-1.).GT.0.01) CXS= 
     &  (1E-4/X)**(PARP(51)-1.) 
    
C...Chebyshev polynomials for x and t expansion.    
        TX(1)=1.    
        TX(2)=VX    
        TX(3)=2.*VX**2-1.   
        TX(4)=4.*VX**3-3.*VX    
        TX(5)=8.*VX**4-8.*VX**2+1.  
        TX(6)=16.*VX**5-20.*VX**3+5.*VX 
        TT(1)=1.    
        TT(2)=VT    
        TT(3)=2.*VT**2-1.   
        TT(4)=4.*VT**3-3.*VT    
        TT(5)=8.*VT**4-8.*VT**2+1.  
        TT(6)=16.*VT**5-20.*VT**3+5.*VT 
    
C...Calculate structure functions.  
        DO 120 KFL=1,6  
        XQSUM=0.    
        DO 110 IT=1,6   
        DO 110 IX=1,6   
  110   XQSUM=XQSUM+CEHLQ(IX,IT,NX,KFL,NSET)*TX(IX)*TT(IT)  
  120   XQ(KFL)=XQSUM*(1.-X)**NEHLQ(KFL,NSET)*CXS   
    
C...Put into output array.  
        XPQ(0)=XQ(4)    
        XPQ(1)=XQ(2)+XQ(3)  
        XPQ(2)=XQ(1)+XQ(3)  
        XPQ(3)=XQ(5)    
        XPQ(4)=XQ(6)    
        XPQ(-1)=XQ(3)   
        XPQ(-2)=XQ(3)   
        XPQ(-3)=XQ(5)   
        XPQ(-4)=XQ(6)   
    
C...Special expansion for bottom (threshold effects).   
        IF(MSTP(54).GE.5) THEN  
          IF(NSET.EQ.1) TMIN=8.1905 
          IF(NSET.EQ.2) TMIN=7.4474 
          IF(T.LE.TMIN) GOTO 140    
          VT=MAX(-1.,MIN(1.,(2.*T-TMAX-TMIN)/(TMAX-TMIN)))  
          TT(1)=1.  
          TT(2)=VT  
          TT(3)=2.*VT**2-1. 
          TT(4)=4.*VT**3-3.*VT  
          TT(5)=8.*VT**4-8.*VT**2+1.    
          TT(6)=16.*VT**5-20.*VT**3+5.*VT   
          XQSUM=0.  
          DO 130 IT=1,6 
          DO 130 IX=1,6 
  130     XQSUM=XQSUM+CEHLQ(IX,IT,NX,7,NSET)*TX(IX)*TT(IT)  
          XPQ(5)=XQSUM*(1.-X)**NEHLQ(7,NSET)    
          XPQ(-5)=XPQ(5)    
  140     CONTINUE  
        ENDIF   
    
C...Special expansion for top (threshold effects).  
        IF(MSTP(54).GE.6) THEN  
          IF(NSET.EQ.1) TMIN=11.5528    
          IF(NSET.EQ.2) TMIN=10.8097    
          TMIN=TMIN+2.*LOG(PMAS(6,1)/30.)   
          TMAX=TMAX+2.*LOG(PMAS(6,1)/30.)   
          IF(T.LE.TMIN) GOTO 160    
          VT=MAX(-1.,MIN(1.,(2.*T-TMAX-TMIN)/(TMAX-TMIN)))  
          TT(1)=1.  
          TT(2)=VT  
          TT(3)=2.*VT**2-1. 
          TT(4)=4.*VT**3-3.*VT  
          TT(5)=8.*VT**4-8.*VT**2+1.    
          TT(6)=16.*VT**5-20.*VT**3+5.*VT   
          XQSUM=0.  
          DO 150 IT=1,6 
          DO 150 IX=1,6 
  150     XQSUM=XQSUM+CEHLQ(IX,IT,NX,8,NSET)*TX(IX)*TT(IT)  
          XPQ(6)=XQSUM*(1.-X)**NEHLQ(8,NSET)    
          XPQ(-6)=XPQ(6)    
  160     CONTINUE  
        ENDIF   
    
      ELSEIF(MSTP(51).EQ.3.OR.MSTP(51).EQ.4) THEN   
C...Proton structure functions from Duke, Owens.    
C...Allowed variable range: 4 GeV2 < Q2 < approx 1E6 GeV2.  
    
C...Determine set, Lambda and s expansion parameter.    
        NSET=MSTP(51)-2 
        IF(NSET.EQ.1) ALAM=0.2  
        IF(NSET.EQ.2) ALAM=0.4  
        IF(MSTP(52).LE.0) THEN  
          SD=0. 
        ELSE    
          SD=LOG(LOG(MAX(Q2,4.)/ALAM**2)/LOG(4./ALAM**2))   
        ENDIF   
    
C...Calculate structure functions.  
        DO 180 KFL=1,5  
        DO 170 IS=1,6   
  170   TS(IS)=CDO(1,IS,KFL,NSET)+CDO(2,IS,KFL,NSET)*SD+    
     &  CDO(3,IS,KFL,NSET)*SD**2    
        IF(KFL.LE.2) THEN   
          XQ(KFL)=X**TS(1)*(1.-X)**TS(2)*(1.+TS(3)*X)/(EULBET(TS(1),    
     &    TS(2)+1.)*(1.+TS(3)*TS(1)/(TS(1)+TS(2)+1.)))  
        ELSE    
          XQ(KFL)=TS(1)*X**TS(2)*(1.-X)**TS(3)*(1.+TS(4)*X+TS(5)*X**2+  
     &    TS(6)*X**3)   
        ENDIF   
  180   CONTINUE    
    
C...Put into output arrays. 
        XPQ(0)=XQ(5)    
        XPQ(1)=XQ(2)+XQ(3)/6.   
        XPQ(2)=3.*XQ(1)-XQ(2)+XQ(3)/6.  
        XPQ(3)=XQ(3)/6. 
        XPQ(4)=XQ(4)    
        XPQ(-1)=XQ(3)/6.    
        XPQ(-2)=XQ(3)/6.    
        XPQ(-3)=XQ(3)/6.    
        XPQ(-4)=XQ(4)   
    
C...Proton structure functions from Diemoz, Ferroni, Longo, Martinelli. 
C...These are accessed via PYHISTFE since the files needed may not always 
C...available.  
      ELSEIF(MSTP(51).GE.11.AND.MSTP(51).LE.13) THEN    
        CALL PYHISTFE(2212,X,Q2,XPQ)  
    
C...Unknown proton parametrization. 
      ELSE  
        WRITE(MSTU(11),1200) MSTP(51)   
      ENDIF 
      GOTO 230  
    
  200 IF((MSTP(51).GE.1.AND.MSTP(51).LE.4).OR.  
     &(MSTP(51).GE.11.AND.MSTP(51).LE.13)) THEN 
C...Pion structure functions from Owens.    
C...Allowed variable range: 4 GeV2 < Q2 < approx 2000 GeV2. 
    
C...Determine set, Lambda and s expansion variable. 
        NSET=1  
        IF(MSTP(51).EQ.2.OR.MSTP(51).EQ.4.OR.MSTP(51).EQ.13) NSET=2 
        IF(NSET.EQ.1) ALAM=0.2  
        IF(NSET.EQ.2) ALAM=0.4  
        IF(MSTP(52).LE.0) THEN  
          SD=0. 
        ELSE    
          SD=LOG(LOG(MAX(Q2,4.)/ALAM**2)/LOG(4./ALAM**2))   
        ENDIF   
    
C...Calculate structure functions.  
        DO 220 KFL=1,4  
        DO 210 IS=1,5   
  210   TS(IS)=COW(1,IS,KFL,NSET)+COW(2,IS,KFL,NSET)*SD+    
     &  COW(3,IS,KFL,NSET)*SD**2    
        IF(KFL.EQ.1) THEN   
          XQ(KFL)=X**TS(1)*(1.-X)**TS(2)/EULBET(TS(1),TS(2)+1.) 
        ELSE    
          XQ(KFL)=TS(1)*X**TS(2)*(1.-X)**TS(3)*(1.+TS(4)*X+TS(5)*X**2)  
        ENDIF   
  220   CONTINUE    
    
C...Put into output arrays. 
        XPQ(0)=XQ(2)    
        XPQ(1)=XQ(3)/6. 
        XPQ(2)=XQ(1)+XQ(3)/6.   
        XPQ(3)=XQ(3)/6. 
        XPQ(4)=XQ(4)    
        XPQ(-1)=XQ(1)+XQ(3)/6.  
        XPQ(-2)=XQ(3)/6.    
        XPQ(-3)=XQ(3)/6.    
        XPQ(-4)=XQ(4)   
    
C...Unknown pion parametrization.   
      ELSE  
        WRITE(MSTU(11),1200) MSTP(51)   
      ENDIF 
    
C...Isospin conjugation for neutron, charge conjugation for antipart.   
  230 IF(KFA.EQ.2112) THEN  
        XPS=XPQ(1)  
        XPQ(1)=XPQ(2)   
        XPQ(2)=XPS  
        XPS=XPQ(-1) 
        XPQ(-1)=XPQ(-2) 
        XPQ(-2)=XPS 
      ENDIF 
      IF(KF.LT.0) THEN  
        DO 240 KFL=1,4  
        XPS=XPQ(KFL)    
        XPQ(KFL)=XPQ(-KFL)  
  240   XPQ(-KFL)=XPS   
      ENDIF 
    
C...Check positivity and reset above maximum allowed flavour.   
      DO 250 KFL=-6,6   
      XPQ(KFL)=MAX(0.,XPQ(KFL)) 
  250 IF(IABS(KFL).GT.MSTP(54)) XPQ(KFL)=0. 

C...consider nuclear effect on the structure function
      	IF((JBT.NE.1.AND.JBT.NE.2).OR.IHPR2(6).EQ.0
     &                  .OR.IHNT2(16).EQ.1) GO TO 400
      	ATNM=IHNT2(2*JBT-1)
      	IF(ATNM.LE.1.0) GO TO 400
      	IF(JBT.EQ.1) THEN
	  BBR2=(YP(1,IHNT2(11))**2+YP(2,IHNT2(11))**2)/1.44/ATNM**0.66666
      	ELSEIF(JBT.EQ.2) THEN
	  BBR2=(YT(1,IHNT2(12))**2+YT(2,IHNT2(12))**2)/1.44/ATNM**0.66666
      	ENDIF
      	BBR2=MIN(1.0,BBR2)
	ABX=(ATNM**0.33333333-1.0)
      	APX=HIPR1(6)*4.0/3.0*ABX*SQRT(1.0-BBR2)
      	AAX=1.192*ALOG(ATNM)**0.1666666
      	RRX=AAX*(X**3-1.2*X**2+0.21*X)+1.0
     &		-(APX-1.079*ABX*SQRT(X)/ALOG(ATNM+1.0))*EXP(-X**2.0/0.01)
      	DO 300 KFL=-6,6
		XPQ(KFL)=XPQ(KFL)*RRX
300   	CONTINUE
C			********consider the nuclear effect on the structure
C				fucntion which also depends on the impact
C				parameter of the nuclear reaction

400   	CONTINUE    
C...Formats for error printouts.    
 1000 FORMAT(' Error: x value outside physical range, x =',1P,E12.3)    
 1100 FORMAT(' Error: illegal particle code for structure function,',   
     &' KF =',I5)   
 1200 FORMAT(' Error: bad value of parameter MSTP(51) in PYHISTFU,',  
     &' MSTP(51) =',I5) 
    
      RETURN    
      END