dnstrf.F

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*72*********************************************************************

      SUBROUTINE dnstrf(X,Q2,XDPQ)

      IMPLICIT NONE

      COMMON /linter/ pari(50),ewqc(2,2,8),qc(8),zl(2,4),zq(2,8),pq(17)
      REAL  pari,ewqc,qc,zl,zq,pq
      SAVE /linter/

*
* to avoid variable conflictions, a second keep element is necessary
* with the same common block name (see LEPTO2)
*

      COMMON /leptou/ cut(14),lst(40),parl(30),
     &                xlp,ylp,w2lp,q2lp,ulp
      REAL cut,parl,xlp,ylp,w2lp,q2lp,ulp
      INTEGER lst
      SAVE /leptou/

      
      REAL x,q2,xdpq,xdu,xdd,xdub,xddb
      dimension xdpq(-6:6)

      IF(lst(15).LE.100) THEN
         WRITE(6,5000) lst(15) 
      ELSEIF(lst(15).gt.100.and.lst(15).lt.1000) THEN !|bs> add LST(15)<1000
         CALL dstfu(2212,x,q2,xdpq)
         IF(pari(11).LE.1.e-06) RETURN
*...  Save polarized d and u valence in proton. 
*...  USE TWO EMPTY CELLS OF ARRAY PARI: PARI(38) AND PARI(39)
         xdd=xdpq(1)
         xdu=xdpq(2)
         pari(38)=xdd
         pari(39)=xdu
C... ALEX: Seems to me that we need these in polleptox.F as well
C...  USE TWO EMPTY CELLS OF ARRAY PARI: PARI(44) AND PARI(45)
         xddb=xdpq(-1)
         xdub=xdpq(-2)
         pari(44)=xddb
         pari(45)=xdub
C...  For nuclear target, mix u- and d-valence distributions.
         IF(lst(39).EQ.0) THEN
               xdpq(1) =(1.-pari(11))*xdd+pari(11)*xdu
               xdpq(2) =(1.-pari(11))*xdu+pari(11)*xdd
               xdpq(-1)=(1.-pari(11))*xddb+pari(11)*xdub
               xdpq(-2)=(1.-pari(11))*xdub+pari(11)*xddb
         ENDIF
      ENDIF

 5000 FORMAT(' Error: unknown polarized structure function;', 
     & ' library, set =',3i5)

      RETURN
      END