      SUBROUTINE CHOICE(MNUM,RR,ICHAN,PROB1,PROB2,PROB3,
     $            AMRX,GAMRX,AMRA,GAMRA,AMRB,GAMRB)
      COMMON / PARMAS / AMTAU,AMNUTA,AMEL,AMNUE,AMMU,AMNUMU
     *                 ,AMPIZ,AMPI,AMRO,GAMRO,AMA1,GAMA1
     *                 ,AMK,AMKZ,AMKST,GAMKST
C
      REAL*4            AMTAU,AMNUTA,AMEL,AMNUE,AMMU,AMNUMU
     *                 ,AMPIZ,AMPI,AMRO,GAMRO,AMA1,GAMA1
     *                 ,AMK,AMKZ,AMKST,GAMKST
C
      AMROP=1.1
      GAMROP=0.36
      AMOM=.782
      GAMOM=0.0084
C     XXXXA CORRESPOND TO S2 CHANNEL !
      IF(MNUM.EQ.0) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =AMA1
       GAMRX=GAMA1
       AMRA =AMRO
       GAMRA=GAMRO
       AMRB =AMRO
       GAMRB=GAMRO
      ELSEIF(MNUM.EQ.1) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =1.57
       GAMRX=0.9
       AMRB =AMKST
       GAMRB=GAMKST
       AMRA =AMRO
       GAMRA=GAMRO
      ELSEIF(MNUM.EQ.2) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =1.57
       GAMRX=0.9
       AMRB =AMKST
       GAMRB=GAMKST
       AMRA =AMRO
       GAMRA=GAMRO
      ELSEIF(MNUM.EQ.3) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =1.27
       GAMRX=0.3
       AMRA =AMKST
       GAMRA=GAMKST
       AMRB =AMKST
       GAMRB=GAMKST
      ELSEIF(MNUM.EQ.4) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =1.27
       GAMRX=0.3
       AMRA =AMKST
       GAMRA=GAMKST
       AMRB =AMKST
       GAMRB=GAMKST
      ELSEIF(MNUM.EQ.5) THEN
       PROB1=0.5
       PROB2=0.5
       AMRX =1.27
       GAMRX=0.3
       AMRA =AMKST
       GAMRA=GAMKST
       AMRB =AMRO
       GAMRB=GAMRO
      ELSEIF(MNUM.EQ.6) THEN
       PROB1=0.4
       PROB2=0.4
       AMRX =1.27
       GAMRX=0.3
       AMRA =AMRO
       GAMRA=GAMRO
       AMRB =AMKST
       GAMRB=GAMKST
      ELSEIF(MNUM.EQ.7) THEN
       PROB1=0.0
       PROB2=1.0
       AMRX =1.27
       GAMRX=0.9
       AMRA =AMRO
       GAMRA=GAMRO
       AMRB =AMRO
       GAMRB=GAMRO
      ELSEIF(MNUM.EQ.8) THEN
       PROB1=0.0
       PROB2=1.0
       AMRX =AMROP
       GAMRX=GAMROP
       AMRB =AMOM
       GAMRB=GAMOM
       AMRA =AMRO
       GAMRA=GAMRO
      ELSEIF(MNUM.EQ.101) THEN
       PROB1=.35
       PROB2=.35
       AMRX =1.2
       GAMRX=.46
       AMRB =AMOM
       GAMRB=GAMOM
       AMRA =AMOM
       GAMRA=GAMOM
      ELSEIF(MNUM.EQ.102) THEN
       PROB1=0.0
       PROB2=0.0
       AMRX =1.4
       GAMRX=.6
       AMRB =AMOM
       GAMRB=GAMOM
       AMRA =AMOM
       GAMRA=GAMOM
      ELSE
       PROB1=0.0
       PROB2=0.0
       AMRX =AMA1
       GAMRX=GAMA1
       AMRA =AMRO
       GAMRA=GAMRO
       AMRB =AMRO
       GAMRB=GAMRO
      ENDIF
C
      IF    (RR.LE.PROB1) THEN
       ICHAN=1
      ELSEIF(RR.LE.(PROB1+PROB2)) THEN
       ICHAN=2
        AX   =AMRA
        GX   =GAMRA
        AMRA =AMRB
        GAMRA=GAMRB
        AMRB =AX
        GAMRB=GX
        PX   =PROB1
        PROB1=PROB2
        PROB2=PX
      ELSE
       ICHAN=3
      ENDIF
C
      PROB3=1.0-PROB1-PROB2
      END
