*
* $Id: dreyin.F,v 1.1.1.1 1996/01/11 14:14:35 mclareni Exp $
*
* $Log: dreyin.F,v $
* Revision 1.1.1.1  1996/01/11 14:14:35  mclareni
* Cojets
*
*
#include "cojets/pilot.h"
      SUBROUTINE DREYIN(KOPTWZ,IDECBO,LEPRAD)
C     ***************************************
C-- ARRANGES INITIAL SET-UP FOR DRELL-YAN PAIR PRODUCTION
C-- IDECBO = IF 0 PHOTON DECAY NOT HANDLED, IF 1-3 PHOTON DECAY IS
C--          HANDLED (1 FOR E-E+, 2 FOR MU-MU+, 3 FOR TAU-TAU+),
C--          IF NEGATIVE DECAY CHANNEL IS GENERATED AT RANDOM.
#if defined(CERNLIB_SINGLE)
      IMPLICIT REAL (A-H,O-Z)
#endif
#if defined(CERNLIB_DOUBLE)
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
#endif
#include "cojets/alqgen.inc"
#include "cojets/data1.inc"
#include "cojets/event.inc"
#include "cojets/evtype.inc"
#include "cojets/itapes.inc"
#include "cojets/radlep.inc"
#include "cojets/weakbo.inc"
      DATA DH/4./
      DATA ICALL/0/
      IF(ICALL.GT.0) RETURN
      ICALL=1
C
      IF(IDECBO.GT.3) GO TO 500
      IF(BOMSMX.GT.ECM*.5) GO TO 600
      IF(BOMSMN.LE.QZEV) GO TO 700
      IF(BOMSMN.GE.BOMSMX) GO TO 800
C
      WEAKBO=DH
      IDECWK=IDECBO
      IRADLP=LEPRAD
      IF(LEPRAD.EQ.2) THEN
        IRADLP=1
        WRITE(ITLIS,1)
1       FORMAT(/1X,'***LEPRAD (KYWQED) HAS BEEN CHANGED TO 1'
     *  /1X,'***FOR THE DRELL-YAN L-L+ CONTINUUM QED RADIATION IN THE'
     *  ,' O(ALPHA) APPROXIMATION IS NOT AVAILABLE')
      ENDIF
      RETURN
C
C-- INCORRECT INPUT
500   WRITE(ITLIS,501) IDECBO
501   FORMAT(////1X,I10,20H IS INCORRECT IDECBO,
     1//1X,'(ACCEPTED ARGUMENTS ARE 0,1,2 AND 3 FOR NO DECAY,'
     2,'ELECTRON,MUON AND TAU DECAY, RESPECTIVELY),'
     *//1X,'OR A NEGATIVE INTEGER TO HAVE THE DECAY CHANNEL'
     *,' GENERATED AT RANDOM.'
     3//1X,20HEXECUTION TERMINATED    )
      STOP
600   WRITE(ITLIS,601) BOMSMX
601   FORMAT(////1X,E12.5,
     1' IS INCORRECT UPPER LIMIT FOR DY GAMMA MASS',
     2//1X,24HTOO LARGE (MAX IS ECM/2)   ,
     3//1X,20HEXECUTION TERMINATED     )
      STOP
700   WRITE(ITLIS,701) BOMSMN,QZEV
701   FORMAT(////1X,E12.5,
     1' IS INCORRECT LOWER LIMIT FOR DY GAMMA MASS' ,
     2//1X,20HSMALLER THAN QZEV =  ,E12.5,
     4//1X,20HEXECUTION TERMINATED      )
      STOP
800   WRITE(ITLIS,801) BOMSMN,BOMSMX
801   FORMAT(////1X,'BOMSMN =',E12.5,'   >   ','BOMSMX =',E12.5
     1//1X,'INCORRECT RANGE FOR DY GAMMA MASS'
     4//1X,20HEXECUTION TERMINATED      )
      STOP
      END