[u/mrichter/AliRoot.git] / GEANT321 / ggeom / gnoctu.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1995/10/24 10:20:52  cernlib
* Geant
*
*
#include "geant321/pilot.h"
*CMZ :  3.21/02 29/03/94  15.41.29  by  S.Giani
*-- Author :
      SUBROUTINE GNOCTU(X, PAR, IACT, SNEXT, SNXT, SAFE)
C.
C.    ******************************************************************
C.    *                                                                *
C.    *      COMPUTE DISTANCE UP TO INTERSECTION WITH 'CTUB'           *
C.    *      VOLUME, FROM OUTSIDE POINT X(1-3) ALONG DIRECTION X(4-6)  *
C.    *                                                                *
C.    *       PAR   (input)  : volume parameters                       *
C.    *       IACT  (input)  : action flag                             *
C.    *         = 0  Compute SAFE only                                 *
C.    *         = 1  Compute SAFE, and SNXT only if SNEXT .GT.new SAFE *
C.    *         = 2  Compute both SAFE and SNXT                        *
C.    *         = 3  Compute SNXT only                                 *
C.    *       SNEXT (input)  : see IACT = 1                            *
C.    *       SNXT  (output) : distance to volume boundary             *
C.    *       SAFE  (output) : shortest distance to any boundary       *
C.    *                                                                *
C.    *    ==>Called by : GNEXT, GNOPCO, GTNEXT                        *
C.    *         Author   A.McPherson   ********                        *
C.    *       MODIFICATION LOG.                                        *
C.    *       18-July-89 M.Guckes modifications due to GEANG 3.13      *
C.    *                                                                *
C.    ******************************************************************
C.
#include "geant321/gconsp.inc"
      DIMENSION X(6),PAR(11),SNP(2),CSP(2)
*
*     ------------------------------------------------------------------
*
      SNXT = BIG
*
* *** Make sure that (-pi).LT.PHI.GE.(+pi)
*
      PH1  = MOD(PAR(4)*DEGRAD,TWOPI)
      PH2  = MOD(PAR(5)*DEGRAD,TWOPI)
      DPHI = PH2 - PH1
      IF(DPHI.LT.TWOPI) THEN
         DPHI = PH2 - PH1
         SNP(1) = SIN(PH1)
         CSP(1) = COS(PH1)
         SNP(2) = SIN(PH2)
         CSP(2) = COS(PH2)
      ELSE
         PH1  = 0.
         PH2  = TWOPI
         DPHI = TWOPI
         SNP(1) = 0.
         CSP(1) = 1.
         SNP(2) = 0.
         CSP(2) = 1.
      ENDIF
C
*
* *** Check that current point is outside the CTUB.  compute SAFE
*
      R02=X(1)*X(1)+X(2)*X(2)
      R=SQRT(R02)
      SAF1=PAR(1)-R
      SAF2=R-PAR(2)
      SAF3 = ( X(3)+PAR(3) )*PAR(8)+X(1)*PAR(6)+X(2)*PAR(7)
      SAF4 = ( X(3)-PAR(3) )*PAR(11)+X(1)*PAR(9)+X(2)*PAR(10)
*
      IF(IACT.EQ.3) GO TO 20
*
*     Phi segment (P. Weidhaas)
*       We compute here the distance (SAF5)
*        to the PHI-segment boundary that is closest to the point:
*
*        SAF5 is only calculated if PHI lies outside the interval
*        [PH1, PH2]. Here PHI is the angle to the given point
*        (thus we only consider SAF5 if the point is outside the
*        PHI-segment : FIOUT > 0.
*        Algorithm to find SAF5 (same as in routine "GNTUBE"):
*        For each PHI-boundary we find the distance from the given
*        point to the outer (at RMAX) point of the segment boundary
*        (DSP1 and DSP2, resp.). If DSP1 < DSP2, we define
*        SAF5 to be the distance to segment PHI1; else we set
*        SAF5 to be the distance to segment PHI2.
      SAF5=0.
      IF(R.GT.0.) THEN
         PHI    = ATAN2(X(2),X(1))
         FIOUT  = DPHI*(PHI-PH1)*(PHI-PH2)
         IF(FIOUT.LE.0.) GO TO 16
         DSP1 = (X(1)-PAR(2)*CSP(1))**2 + (X(2)-PAR(2)*SNP(1))**2
         DSP2 = (X(1)-PAR(2)*CSP(2))**2 + (X(2)-PAR(2)*SNP(2))**2
         IF(DSP1.LE.DSP2) THEN
            SAF5 = ABS(X(1)*SNP(1) - X(2)*CSP(1))
         ELSE
            SAF5 = ABS(X(1)*SNP(2) - X(2)*CSP(2))
         ENDIF
      ENDIF
   16 CONTINUE
*
*     Compute SAFE
      SAFE = 0.
      IF(SAF1.GT.SAFE) SAFE = SAF1
      IF(SAF2.GT.SAFE) SAFE = SAF2
      IF(SAF3.GT.SAFE) SAFE = SAF3
      IF(SAF4.GT.SAFE) SAFE = SAF4
      IF(SAF5.GT.SAFE) SAFE = SAF5
*
*     Point inside the volume ?
      IF(SAFE.EQ.0.) THEN
         SNXT = -10.
         GO TO 999
      ENDIF
*
      IF(IACT.EQ.0)                   GO TO 999
      IF(IACT.EQ.1.AND.SAFE.GT.SNEXT) GO TO 999
*
   20 CONTINUE
*
* *** Compute SNXT
*
      SMAX=BIG
      V1 = X(4)*PAR(6)+X(5)*PAR(7)+X(6)*PAR(8)
      V2 = X(4)*PAR(9)+X(5)*PAR(10)+X(6)*PAR(11)
      IF( V1 .GE. 0.0 .AND. SAF3 .GE. 0.0 ) GO TO 999
      IF( V2 .GE. 0.0 .AND. SAF4 .GE. 0.0 ) GO TO 999
C
      IF( SAF3 .GT. 0.0 .AND. SAF4 .LE. 0.0 ) THEN
        SMIN = -SAF3/V1
        IF( V2 .GT. 0 ) THEN
          SMAX = -SAF4/V2
        ELSE
          SMAX = BIG
        ENDIF
      ELSEIF( SAF4 .GT. 0.0 .AND. SAF3 .LE. 0.0 ) THEN
        SMIN = -SAF4/V2
        IF( V1 .GT. 0 ) THEN
          SMAX = -SAF3/V1
        ELSE
          SMAX = BIG
        ENDIF
      ELSEIF( SAF3 .LE. 0.0 .AND. SAF4 .LE. 0.0 ) THEN
        SMIN = 0.0
        SMAX = BIG
        IF( V1 .GT. 0.0 ) SMAX = -SAF3/V1
        IF( V2 .GT. 0.0 .AND. SMAX .GT. -SAF4/V2 ) SMAX = -SAF4/V2
      ENDIF
*
      SMIN1=SMIN
      SMAX1=-1.0
      SMIN2=SMIN
      SMAX2=SMAX
C
      DXY2=(1+X(6))*(1-X(6))
      IF(DXY2.LT.1.0E-10.AND.(R.LT.PAR(1)
     +   .OR.R.GT.PAR(2)))GO TO 999
      IF(DXY2.EQ.0.) GO TO 30
C
      BA=(X(1)*X(4)+X(2)*X(5))/DXY2
      IF(R.GE.PAR(2).AND.BA.GE.0.0) GO TO 999
C
      CA=(R02-PAR(2)*PAR(2))/DXY2
      DISC=BA*BA-CA
      IF(DISC.LE.0.0) GO TO 999
C
      RDISC=SQRT(DISC)
      SMAR=-BA+RDISC
      IF(SMAR.LT.SMAX) SMAX=SMAR
      SMIR=-BA-RDISC
      IF(SMIR.GT.SMIN) SMIN=SMIR
      IF(SMAX.LE.SMIN) GO TO 999
C
      CA=(R02-PAR(1)*PAR(1))/DXY2
      DISC=BA*BA-CA
C
      SMIN1=SMIN
      SMAX1=-1.0
      SMIN2=SMIN
      SMAX2=SMAX
C
      IF(DISC.LE.0.0) GO TO 30
      RDISC=SQRT(DISC)
      SMI2=-BA+RDISC
      IF(SMI2.GT.SMIN2)SMIN2=SMI2
      SMAX1=-BA-RDISC
      IF(SMAX.LT.SMAX1) SMAX1=SMAX
C
   30 CONTINUE
C
      IF( PAR(4) .EQ. 0.0 .AND. PAR(5) .EQ. 360.0 ) GO TO 120
C
C                   Now do the phi stuff.
C
      DPSGN=X(1)*X(5)-X(2)*X(4)
      ISMIN=0
      ISMAX=0
C
      TSGN=SNP(1)
      TCSG=CSP(1)
      DEN=X(4)*TSGN-X(5)*TCSG
      IF(DEN.EQ.0.0) GO TO 40
      SNL=(X(2)*TCSG-X(1)*TSGN)/DEN
      IF(ABS(TSGN).GT.1.E-6.AND.(X(2)+SNL*X(5))*TSGN.LT.0.) GO TO 40
      IF(ABS(TCSG).GT.1.E-6.AND.(X(1)+SNL*X(4))*TCSG.LT.0.) GO TO 40
C
      ISMIN=1
      SMIN=SNL
      IF(DPSGN.GT.0.0) GO TO 40
      ISMIN=0
      ISMAX=1
      SMAX=SNL
C
   40 CONTINUE
C
      TSGN=SNP(2)
      TCSG=CSP(2)
      DEN=X(4)*TSGN-X(5)*TCSG
      IF(DEN.EQ.0.0) GO TO 60
      SNH=(X(2)*TCSG-X(1)*TSGN)/DEN
      IF(ABS(TSGN).GT.1.E-6.AND.(X(2)+SNH*X(5))*TSGN.LT.0.) GO TO 60
      IF(ABS(TCSG).GT.1.E-6.AND.(X(1)+SNH*X(4))*TCSG.LT.0.) GO TO 60
      IF(DPSGN.LT.0.0) GO TO 50
      ISMAX=1
      SMAX=SNH
      GO TO 60
C
   50 CONTINUE
      ISMIN=1
      SMIN=SNH
C
   60 CONTINUE
C
      IF(ISMIN.EQ.0.OR.ISMAX.EQ.0) GO TO 90
      IF(SMAX.LT.0.0.AND.SMAX.GT.SMIN) GO TO 999
      IF(SMIN.LT.0.0) SMIN=0.0
      IF(SMAX.LT.0.0) GO TO 110
      IF(SMAX.GT.SMIN) GO TO 70
C
C                         SMAX +VE and less than SMIN - 2 allowed
C                         regions.
C
      IF(SMAX.GT.SMIN1.AND.SMAX1.GT.SMIN1) GO TO 130
      IF(SMIN.GT.SMIN1) SMIN1=SMIN
      IF(SMAX1.GT.SMIN1) GO TO 130
      IF(SMAX.GT.SMIN2) GO TO 140
      IF(SMIN.GT.SMAX2) GO TO 999
      IF(SMIN.GT.SMIN2) SMIN2=SMIN
      GO TO 140
C
   70 CONTINUE
      IF(SMIN.GT.SMIN1) SMIN1=SMIN
      IF(SMAX.LT.SMAX1) SMAX1=SMAX
      IF(SMAX1.LT.SMIN1) GO TO 80
      GO TO 130
C
   80 CONTINUE
      IF(SMIN.GT.SMIN2) SMIN2=SMIN
      IF(SMAX.LT.SMAX2) SMAX2=SMAX
      IF(SMAX2.LT.SMIN2) GO TO 999
      GO TO 140
C
   90 CONTINUE
      IF(ISMIN.EQ.1) GO TO 110
      IF(ISMAX.EQ.0) GO TO 100
      IF(SMAX.LT.SMAX1) SMAX1=SMAX
      IF(SMAX.LT.SMAX2) SMAX2=SMAX
      GO TO 120
C
  100 CONTINUE
      DPH=PAR(5)-PAR(4)
      IF(DPH.LT.180.0.AND.DPH.GT.0.0) GO TO 999
      IF(DPH.LT.-180.0) GO TO 999
      GO TO 120
C
  110 CONTINUE
      IF(SMIN.GT.SMIN1) SMIN1=SMIN
      IF(SMAX1.GT.SMIN1) GO TO 130
      IF(SMIN.GT.SMIN2) SMIN2=SMIN
      IF(SMAX2.LT.SMIN2) GO TO 999
      GO TO 140
C
  120 CONTINUE
      IF(SMAX1.GT.SMIN1) GO TO 130
      IF(SMAX2.GT.SMIN2) GO TO 140
      GO TO 999
C
  130 CONTINUE
      IF(SMIN1.LE.0.)GO TO 999
      IF(SNXT.GT.SMIN1) SNXT=SMIN1
      GO TO 999
C
  140 CONTINUE
      IF(SMIN2.LE.0.)GO TO 999
      IF(SNXT.GT.SMIN2) SNXT=SMIN2
C
  999 CONTINUE
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1995/10/24 10:20:52 cernlib
	6	* Geant
	7	*
	8	*
	9	#include "geant321/pilot.h"
	10	*CMZ : 3.21/02 29/03/94 15.41.29 by S.Giani
	11	*-- Author :
	12	SUBROUTINE GNOCTU(X, PAR, IACT, SNEXT, SNXT, SAFE)
	13	C.
	14	C. ******************************************************************
	15	C. * *
	16	C. * COMPUTE DISTANCE UP TO INTERSECTION WITH 'CTUB' *
	17	C. * VOLUME, FROM OUTSIDE POINT X(1-3) ALONG DIRECTION X(4-6) *
	18	C. * *
	19	C. * PAR (input) : volume parameters *
	20	C. * IACT (input) : action flag *
	21	C. * = 0 Compute SAFE only *
	22	C. * = 1 Compute SAFE, and SNXT only if SNEXT .GT.new SAFE *
	23	C. * = 2 Compute both SAFE and SNXT *
	24	C. * = 3 Compute SNXT only *
	25	C. * SNEXT (input) : see IACT = 1 *
	26	C. * SNXT (output) : distance to volume boundary *
	27	C. * SAFE (output) : shortest distance to any boundary *
	28	C. * *
	29	C. * ==>Called by : GNEXT, GNOPCO, GTNEXT *
	30	C. * Author A.McPherson ******** *
	31	C. * MODIFICATION LOG. *
	32	C. * 18-July-89 M.Guckes modifications due to GEANG 3.13 *
	33	C. * *
	34	C. ******************************************************************
	35	C.
	36	#include "geant321/gconsp.inc"
	37	DIMENSION X(6),PAR(11),SNP(2),CSP(2)
	38	*
	39	* ------------------------------------------------------------------
	40	*
	41	SNXT = BIG
	42	*
	43	* *** Make sure that (-pi).LT.PHI.GE.(+pi)
	44	*
	45	PH1 = MOD(PAR(4)*DEGRAD,TWOPI)
	46	PH2 = MOD(PAR(5)*DEGRAD,TWOPI)
	47	DPHI = PH2 - PH1
	48	IF(DPHI.LT.TWOPI) THEN
	49	DPHI = PH2 - PH1
	50	SNP(1) = SIN(PH1)
	51	CSP(1) = COS(PH1)
	52	SNP(2) = SIN(PH2)
	53	CSP(2) = COS(PH2)
	54	ELSE
	55	PH1 = 0.
	56	PH2 = TWOPI
	57	DPHI = TWOPI
	58	SNP(1) = 0.
	59	CSP(1) = 1.
	60	SNP(2) = 0.
	61	CSP(2) = 1.
	62	ENDIF
	63	C
	64	*
65	* *** Check that current point is outside the CTUB. compute SAFE
66	*
67	R02=X(1)X(1)+X(2)X(2)
68	R=SQRT(R02)
69	SAF1=PAR(1)-R
70	SAF2=R-PAR(2)
71	SAF3 = ( X(3)+PAR(3) )PAR(8)+X(1)PAR(6)+X(2)*PAR(7)
72	SAF4 = ( X(3)-PAR(3) )PAR(11)+X(1)PAR(9)+X(2)*PAR(10)
73	*
74	IF(IACT.EQ.3) GO TO 20
75	*
76	* Phi segment (P. Weidhaas)
77	* We compute here the distance (SAF5)
78	* to the PHI-segment boundary that is closest to the point:
79	*
80	* SAF5 is only calculated if PHI lies outside the interval
81	* [PH1, PH2]. Here PHI is the angle to the given point
82	* (thus we only consider SAF5 if the point is outside the
83	* PHI-segment : FIOUT > 0.
84	* Algorithm to find SAF5 (same as in routine "GNTUBE"):
85	* For each PHI-boundary we find the distance from the given
86	* point to the outer (at RMAX) point of the segment boundary
87	* (DSP1 and DSP2, resp.). If DSP1 < DSP2, we define
88	* SAF5 to be the distance to segment PHI1; else we set
89	* SAF5 to be the distance to segment PHI2.
90	SAF5=0.
91	IF(R.GT.0.) THEN
92	PHI = ATAN2(X(2),X(1))
93	FIOUT = DPHI(PHI-PH1)(PHI-PH2)
94	IF(FIOUT.LE.0.) GO TO 16
95	DSP1 = (X(1)-PAR(2)CSP(1))2 + (X(2)-PAR(2)SNP(1))**2
96	DSP2 = (X(1)-PAR(2)CSP(2))2 + (X(2)-PAR(2)SNP(2))**2
97	IF(DSP1.LE.DSP2) THEN
98	SAF5 = ABS(X(1)SNP(1) - X(2)CSP(1))
99	ELSE
100	SAF5 = ABS(X(1)SNP(2) - X(2)CSP(2))
101	ENDIF
102	ENDIF
103	16 CONTINUE
104	*
105	* Compute SAFE
106	SAFE = 0.
107	IF(SAF1.GT.SAFE) SAFE = SAF1
108	IF(SAF2.GT.SAFE) SAFE = SAF2
109	IF(SAF3.GT.SAFE) SAFE = SAF3
110	IF(SAF4.GT.SAFE) SAFE = SAF4
111	IF(SAF5.GT.SAFE) SAFE = SAF5
112	*
113	* Point inside the volume ?
114	IF(SAFE.EQ.0.) THEN
115	SNXT = -10.
116	GO TO 999
117	ENDIF
118	*
119	IF(IACT.EQ.0) GO TO 999
120	IF(IACT.EQ.1.AND.SAFE.GT.SNEXT) GO TO 999
121	*
122	20 CONTINUE
123	*
124	* *** Compute SNXT
125	*
126	SMAX=BIG
127	V1 = X(4)PAR(6)+X(5)PAR(7)+X(6)*PAR(8)
128	V2 = X(4)PAR(9)+X(5)PAR(10)+X(6)*PAR(11)
129	IF( V1 .GE. 0.0 .AND. SAF3 .GE. 0.0 ) GO TO 999
130	IF( V2 .GE. 0.0 .AND. SAF4 .GE. 0.0 ) GO TO 999
131	C
132	IF( SAF3 .GT. 0.0 .AND. SAF4 .LE. 0.0 ) THEN
133	SMIN = -SAF3/V1
134	IF( V2 .GT. 0 ) THEN
135	SMAX = -SAF4/V2
136	ELSE
137	SMAX = BIG
138	ENDIF
139	ELSEIF( SAF4 .GT. 0.0 .AND. SAF3 .LE. 0.0 ) THEN
140	SMIN = -SAF4/V2
141	IF( V1 .GT. 0 ) THEN
142	SMAX = -SAF3/V1
143	ELSE
144	SMAX = BIG
145	ENDIF
146	ELSEIF( SAF3 .LE. 0.0 .AND. SAF4 .LE. 0.0 ) THEN
147	SMIN = 0.0
148	SMAX = BIG
149	IF( V1 .GT. 0.0 ) SMAX = -SAF3/V1
150	IF( V2 .GT. 0.0 .AND. SMAX .GT. -SAF4/V2 ) SMAX = -SAF4/V2
151	ENDIF
152	*
153	SMIN1=SMIN
154	SMAX1=-1.0
155	SMIN2=SMIN
156	SMAX2=SMAX
157	C
158	DXY2=(1+X(6))*(1-X(6))
159	IF(DXY2.LT.1.0E-10.AND.(R.LT.PAR(1)
160	+ .OR.R.GT.PAR(2)))GO TO 999
161	IF(DXY2.EQ.0.) GO TO 30
162	C
163	BA=(X(1)X(4)+X(2)X(5))/DXY2
164	IF(R.GE.PAR(2).AND.BA.GE.0.0) GO TO 999
165	C
166	CA=(R02-PAR(2)*PAR(2))/DXY2
167	DISC=BA*BA-CA
168	IF(DISC.LE.0.0) GO TO 999
169	C
170	RDISC=SQRT(DISC)
171	SMAR=-BA+RDISC
172	IF(SMAR.LT.SMAX) SMAX=SMAR
173	SMIR=-BA-RDISC
174	IF(SMIR.GT.SMIN) SMIN=SMIR
175	IF(SMAX.LE.SMIN) GO TO 999
176	C
177	CA=(R02-PAR(1)*PAR(1))/DXY2
178	DISC=BA*BA-CA
179	C
180	SMIN1=SMIN
181	SMAX1=-1.0
182	SMIN2=SMIN
183	SMAX2=SMAX
184	C
185	IF(DISC.LE.0.0) GO TO 30
186	RDISC=SQRT(DISC)
187	SMI2=-BA+RDISC
188	IF(SMI2.GT.SMIN2)SMIN2=SMI2
189	SMAX1=-BA-RDISC
190	IF(SMAX.LT.SMAX1) SMAX1=SMAX
191	C
192	30 CONTINUE
193	C
194	IF( PAR(4) .EQ. 0.0 .AND. PAR(5) .EQ. 360.0 ) GO TO 120
195	C
196	C Now do the phi stuff.
197	C
198	DPSGN=X(1)X(5)-X(2)X(4)
199	ISMIN=0
200	ISMAX=0
201	C
202	TSGN=SNP(1)
203	TCSG=CSP(1)
204	DEN=X(4)TSGN-X(5)TCSG
205	IF(DEN.EQ.0.0) GO TO 40
206	SNL=(X(2)TCSG-X(1)TSGN)/DEN
207	IF(ABS(TSGN).GT.1.E-6.AND.(X(2)+SNLX(5))TSGN.LT.0.) GO TO 40
208	IF(ABS(TCSG).GT.1.E-6.AND.(X(1)+SNLX(4))TCSG.LT.0.) GO TO 40
209	C
210	ISMIN=1
211	SMIN=SNL
212	IF(DPSGN.GT.0.0) GO TO 40
213	ISMIN=0
214	ISMAX=1
215	SMAX=SNL
216	C
217	40 CONTINUE
218	C
219	TSGN=SNP(2)
220	TCSG=CSP(2)
221	DEN=X(4)TSGN-X(5)TCSG
222	IF(DEN.EQ.0.0) GO TO 60
223	SNH=(X(2)TCSG-X(1)TSGN)/DEN
224	IF(ABS(TSGN).GT.1.E-6.AND.(X(2)+SNHX(5))TSGN.LT.0.) GO TO 60
225	IF(ABS(TCSG).GT.1.E-6.AND.(X(1)+SNHX(4))TCSG.LT.0.) GO TO 60
226	IF(DPSGN.LT.0.0) GO TO 50
227	ISMAX=1
228	SMAX=SNH
229	GO TO 60
230	C
231	50 CONTINUE
232	ISMIN=1
233	SMIN=SNH
234	C
235	60 CONTINUE
236	C
237	IF(ISMIN.EQ.0.OR.ISMAX.EQ.0) GO TO 90
238	IF(SMAX.LT.0.0.AND.SMAX.GT.SMIN) GO TO 999
239	IF(SMIN.LT.0.0) SMIN=0.0
240	IF(SMAX.LT.0.0) GO TO 110
241	IF(SMAX.GT.SMIN) GO TO 70
242	C
243	C SMAX +VE and less than SMIN - 2 allowed
244	C regions.
245	C
246	IF(SMAX.GT.SMIN1.AND.SMAX1.GT.SMIN1) GO TO 130
247	IF(SMIN.GT.SMIN1) SMIN1=SMIN
248	IF(SMAX1.GT.SMIN1) GO TO 130
249	IF(SMAX.GT.SMIN2) GO TO 140
250	IF(SMIN.GT.SMAX2) GO TO 999
251	IF(SMIN.GT.SMIN2) SMIN2=SMIN
252	GO TO 140
253	C
254	70 CONTINUE
255	IF(SMIN.GT.SMIN1) SMIN1=SMIN
256	IF(SMAX.LT.SMAX1) SMAX1=SMAX
257	IF(SMAX1.LT.SMIN1) GO TO 80
258	GO TO 130
259	C
260	80 CONTINUE
261	IF(SMIN.GT.SMIN2) SMIN2=SMIN
262	IF(SMAX.LT.SMAX2) SMAX2=SMAX
263	IF(SMAX2.LT.SMIN2) GO TO 999
264	GO TO 140
265	C
266	90 CONTINUE
267	IF(ISMIN.EQ.1) GO TO 110
268	IF(ISMAX.EQ.0) GO TO 100
269	IF(SMAX.LT.SMAX1) SMAX1=SMAX
270	IF(SMAX.LT.SMAX2) SMAX2=SMAX
271	GO TO 120
272	C
273	100 CONTINUE
274	DPH=PAR(5)-PAR(4)
275	IF(DPH.LT.180.0.AND.DPH.GT.0.0) GO TO 999
276	IF(DPH.LT.-180.0) GO TO 999
277	GO TO 120
278	C
279	110 CONTINUE
280	IF(SMIN.GT.SMIN1) SMIN1=SMIN
281	IF(SMAX1.GT.SMIN1) GO TO 130
282	IF(SMIN.GT.SMIN2) SMIN2=SMIN
283	IF(SMAX2.LT.SMIN2) GO TO 999
284	GO TO 140
285	C
286	120 CONTINUE
287	IF(SMAX1.GT.SMIN1) GO TO 130
288	IF(SMAX2.GT.SMIN2) GO TO 140
289	GO TO 999
290	C
291	130 CONTINUE
292	IF(SMIN1.LE.0.)GO TO 999
293	IF(SNXT.GT.SMIN1) SNXT=SMIN1
294	GO TO 999
295	C
296	140 CONTINUE
297	IF(SMIN2.LE.0.)GO TO 999
298	IF(SNXT.GT.SMIN2) SNXT=SMIN2
299	C
300	999 CONTINUE
301	END