PDF/spdf/bxf3.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.4  2000/09/18 10:02:35  hristov
   6 * Makefile added to PDF8
   7 *
   8 * Revision 1.1.1.2  1996/10/30 08:27:39  cernlib
   9 * Version 7.04
  10 *
  11 * Revision 1.1.1.1  1996/04/12 15:29:04  plothow
  12 * Version 7.01
  13 *
  14 *
  15 #include "pdf/pilot.h"
  16       SUBROUTINE BXF3 (X,QQ,XF3)
  17 C.......................................................................
  18 C.
  19 C.    F3   (GIVES VALENCE FOR U AND D)
  20 C.
  21 C.......................................................................
  22 #include "pdf/impdp.inc"
  23 #if defined(CERNLIB_DOUBLE)
  24       DOUBLE PRECISION
  25 #endif
  26 #if defined(CERNLIB_SINGLE)
  27       REAL
  28 #endif
  29      +       BBETA
  30       DATA XLAM /0.47D00/, Q02/5.D0/
  31       DATA ONED/1.D0/, FIVED2/5.2D0/
  32 C
  33       S = LOG( LOG( MAX(FIVED2,QQ)/XLAM**2)/ LOG( Q02/XLAM**2))
  34       ETA1=0.56D00-0.92D00*S*4.00D00/25.00D00
  35       ETA2=2.71D00+5.08D00*S*4.00D00/25.00D00
  36       XF3=(X**ETA1)*((ONED-X)**ETA2)/BBETA(ETA1,ONED+ETA2)
  37       XF3=3.0D00*XF3
  38       RETURN
  39       END