PDF/spdf/bxf3.F

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