C-----------------------------------------------------------------------
C  Convert Euler angles to Kappa (IEK = 0) or vice-versa (IEK = 1)
C-----------------------------------------------------------------------
      SUBROUTINE EULKAP (IEK,OME,CHE,PHE,OMK,RKA,PHK,ISTTUS)
      COMMON /CADCON/ ALPHA,APMIN,APMAX,MAXVAR,MINVAR,
     $                IHOLE,IVSLIT,IHSLIT,INEG45,IPOS45,IUPHAF,ILOHAF,
     $                VUTHT,VUOME,VUCHI,VUPHI,IPORT,IBAUD
      PARAMETER (RA = 57.2958)
C      ALPHA  = 49.98907
C      ALPHA  = ALPHA/RA
      SALPHA = SIN(ALPHA/RA)
      CALPHA = COS(ALPHA/RA)
      ISTTUS = 0
C-----------------------------------------------------------------------
C  IEK = 0  Euler to Kappa
C-----------------------------------------------------------------------
      IF (IEK .EQ. 0) THEN
        SCO2 = SIN(ONE80(CHE)/(2.0*RA))
        BOT  = SALPHA*SALPHA - SCO2*SCO2
        IF (BOT .LE. 0.0) THEN
          ISTTUS = 1
          RETURN
        ENDIF
        RKAO2 = ATAN(SCO2/SQRT(BOT))
        RKA   = ONE80(2.0*RA*RKAO2)
        DELTA = RA*ATAN(CALPHA*SIN(RKAO2)/COS(RKAO2))
        OMK   = ONE80(OME - DELTA)
        PHK   = ONE80(PHE - DELTA)
C-----------------------------------------------------------------------
C  IEK = 1  Kappa to Euler 
C-----------------------------------------------------------------------
      ELSE
        RKAO2 = RKA/(2.0*RA)
        CHE   = ONE80(2.0*RA*ASIN(SALPHA*SIN(RKAO2)))
        DELTA = RA*ATAN(CALPHA*SIN(RKAO2)/COS(RKAO2))
        OME   = ONE80(OMK + DELTA)
        PHE   = ONE80(PHK + DELTA)
      ENDIF
      RETURN
      END
C-----------------------------------------------------------------------
C  Function to put angles in the range -180 to 180
C-----------------------------------------------------------------------
      REAL FUNCTION ONE80 (X)
      XX = X
      IF (X .LT. -180.00) XX = X + 360.00
      IF (X .GT.  180.00) XX = X - 360.00
      ONE80 = XX
      RETURN
      END