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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 GNHYPE (X, PAR, IACT, SNEXT, SNXT, SAFE) | |
13 | C. | |
14 | C. ****************************************************************** | |
15 | C. * * | |
16 | C. * COMPUTE DISTANCE UP TO INTERSECTION WITH HYPErboloid * | |
17 | C. * VOLUME FROM INSIDE POINT X(1-3) ALONG DIRECTION X(4-6) * | |
18 | C. * * | |
19 | C. * PAR (input) : volume parameters * | |
20 | C. * inner radius * | |
21 | C. * outer radius * | |
22 | C. * half length in z * | |
23 | C. * straw stereo angle in degrees * | |
24 | C. * r**2 = (z*tan(theta))**2 + a**2 * | |
25 | C. * * | |
26 | C. * IACT (input) : action flag * | |
27 | C. * = 0 Compute SAFE only * | |
28 | C. * = 1 Compute SAFE, and SNXT only if SNEXT .GT.new SAFE * | |
29 | C. * = 2 Compute both SAFE and SNXT * | |
30 | C. * = 3 Compute SNXT only * | |
31 | C. * SNEXT (input) : see IACT = 1 * | |
32 | C. * SNXT (output) : distance to volume boundary * | |
33 | C. * SAFE (output) : shortest distance to any boundary * | |
34 | C. * * | |
35 | C. * ==>Called by : GNEXT, GTNEXT * | |
36 | C. * Authors M.J. Corden, A.Palounek * | |
37 | C. * * | |
38 | C. ****************************************************************** | |
39 | C. | |
40 | #include "geant321/gconsp.inc" | |
41 | DIMENSION X(6),PAR(4) | |
42 | ||
43 | C------------------------------------------------------------- | |
44 | ||
45 | SNXT = BIG | |
46 | R2 = X(1)*X(1) + X(2)*X(2) | |
47 | TANTHS=(TAN(PAR(4)*DEGRAD))**2 | |
48 | ||
49 | C ------------------------------------------------- | |
50 | C | Compute safety-distance 'SAFE' (P.Weidhaas) | | |
51 | C ------------------------------------------------- | |
52 | ||
53 | SAFZ1 = PAR(3) - X(3) | |
54 | SAFZ2 = PAR(3) + X(3) | |
55 | ||
56 | IF (IACT .LT. 3) THEN | |
57 | ||
58 | C tube version: | |
59 | C R = SQRT (R2) | |
60 | C IF (PAR(1).NE.0.) THEN | |
61 | C SAFR1 = R - PAR(1) | |
62 | C ELSE | |
63 | C SAFR1 = BIG | |
64 | C ENDIF | |
65 | C SAFR2 = PAR(2) - R | |
66 | C | |
67 | C SAFE = MIN (SAFZ1, SAFZ2, SAFR1, SAFR2) | |
68 | C | |
69 | C simple, safe choice for hyperboloid for now: | |
70 | SAFE=0. | |
71 | C | |
72 | IF (IACT .EQ. 0) GO TO 999 | |
73 | IF (IACT .EQ. 1) THEN | |
74 | IF (SNEXT .LT. SAFE) GO TO 999 | |
75 | ENDIF | |
76 | ENDIF | |
77 | ||
78 | C ------------------------------------------------ | |
79 | C | Compute vector-distance 'SNXT' (McPherson) | | |
80 | C ------------------------------------------------ | |
81 | ||
82 | C | |
83 | C Compute intersection with z-boundaries. | |
84 | C | |
85 | IF(X(6).GT.0.)THEN | |
86 | SNXT=SAFZ1/X(6) | |
87 | ELSEIF(X(6).LT.0.)THEN | |
88 | SNXT=-SAFZ2/X(6) | |
89 | ENDIF | |
90 | C | |
91 | C Compute intercepts with inner & outer curved surfaces: | |
92 | C | |
93 | A = X(4)**2 + X(5)**2 - X(6)**2*TANTHS | |
94 | B = X(1)*X(4) + X(2)*X(5) - X(3)*X(6)*TANTHS | |
95 | ||
96 | DO 38 NCYL =1,2 | |
97 | C = R2 - X(3)**2*TANTHS - PAR(NCYL)**2 | |
98 | SURD = B**2 - A*C | |
99 | IF(SURD.GT.0.) THEN | |
100 | SURD=SQRT(SURD) | |
101 | DIST1=(-B+SURD)/A | |
102 | IF(DIST1.GT.0.) SNXT=MIN(SNXT,DIST1) | |
103 | DIST2=(-B-SURD)/A | |
104 | IF(DIST2.GT.0.) SNXT=MIN(SNXT,DIST2) | |
105 | C not necessary to compute intercept with outer surface | |
106 | C if there is a positive intercept with inner surface: | |
107 | IF(DIST1.GT.0. .OR. DIST2.GT.0.) GO TO 999 | |
108 | ENDIF | |
109 | 38 CONTINUE | |
110 | C | |
111 | 999 CONTINUE | |
112 | END |