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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1995/10/24 10:20:57 cernlib | |
6 | * Geant | |
7 | * | |
8 | * | |
9 | #include "geant321/pilot.h" | |
10 | *CMZ : 3.21/02 29/03/94 15.41.31 by S.Giani | |
11 | *-- Author : | |
12 | * | |
13 | FUNCTION GVSAFE (XYZ, C1, C, NC) | |
14 | ************************************************************************ | |
15 | * * | |
16 | * GVSAFE Calculates the distance from a point YB 870511 * | |
17 | * to a surface, and the gradient in this point. * | |
18 | * This is an approximation of the distance, which is smaller * | |
19 | * than the real distance. * | |
20 | * * | |
21 | * Input : XYZ point coordinates * | |
22 | * C1 constant coefficient from the surface * | |
23 | * C(1) number of non constant coefficients from * | |
24 | * the surface * | |
25 | * C(2),C(3),... non constant coefficients from the surface * | |
26 | * NC total number of coefficients from the surface * | |
27 | * * | |
28 | * Extra OUTPUT: COMMON/SLATE/ISLATE(2) ISLATE(2)=ISIGN (from GVSIGN) * | |
29 | * SLATE(10) - value of S(X) * | |
30 | * SLATE(11:13) - gradient * | |
31 | * SLATE(14) - normalisation factor for distance * | |
32 | * SLATE(15) - normalisation factor for gradient * | |
33 | * * | |
34 | ************************************************************************ | |
35 | COMMON /SLATE/ SLATE (40) | |
36 | INTEGER ISLATE(40) | |
37 | EQUIVALENCE (SLATE,ISLATE) | |
38 | EQUIVALENCE (JDUMM,SLATE(2)) | |
39 | REAL XYZ(3) , C(*) | |
40 | INTEGER GVSIGN | |
41 | *----------------------------------------------------------------------- | |
42 | SLATE(14) = 1. | |
43 | SLATE(15) = 1. | |
44 | IF (NC.NE.2) GO TO 200 | |
45 | * | |
46 | * case with simplified surface X=C0, Y=C0, Z=C0, X*2+Y*2=C0 | |
47 | * (happens only when initialisation is done) | |
48 | * | |
49 | IAX = C(2) | |
50 | SLATE(11) = 0. | |
51 | SLATE(12) = 0. | |
52 | SLATE(13) = 0. | |
53 | IF (IAX.LE.3) THEN | |
54 | SLATE(10) = C1 + XYZ(IAX) | |
55 | SLATE(IAX+10) = 1. | |
56 | CC = SLATE(10) | |
57 | ELSE | |
58 | RXY2 = XYZ(1)**2 + XYZ(2)**2 | |
59 | RXY = SQRT(RXY2) | |
60 | SLATE(10) = (RXY2 - C1**2) | |
61 | SLATE(11) = 2.*XYZ(1) | |
62 | SLATE(12) = 2.*XYZ(2) | |
63 | SLATE(15) = 2.*RXY | |
64 | SLATE(14) = (RXY-C1) | |
65 | CC = SLATE(10)/SLATE(14) | |
66 | ENDIF | |
67 | IF (SLATE(10)) 101,102,103 | |
68 | 101 ISLATE(2) = -1 | |
69 | GO TO 999 | |
70 | 102 ISLATE(2) = 0 | |
71 | GO TO 999 | |
72 | 103 ISLATE(2) = +1 | |
73 | GO TO 999 | |
74 | * | |
75 | * case with surfaces with 4, 7 or 10 coefficients (normal case) | |
76 | * | |
77 | 200 JDUMM = GVSIGN (XYZ, C1, C, NC) | |
78 | CC = SLATE(1) | |
79 | SLATE(10) = SLATE(1) | |
80 | SLATE(11) = C(2) | |
81 | SLATE(12) = C(3) | |
82 | SLATE(13) = C(4) | |
83 | IF (NC .EQ. 4) GO TO 999 | |
84 | IF (NC .EQ. 7) THEN | |
85 | AA = 1. | |
86 | ELSE | |
87 | CCC AA = C(5)**2+C(6)**2+C(7)**2CCC AA = C(5)**2+C(6)**2+C(7)**2 | |
88 | CCC ++ 0.5*(C(8)**2+C(9)**2+C(10)**2) | |
89 | CCC AA = SQRT(AA) | |
90 | AA = 2.0 | |
91 | ENDIF | |
92 | CALL GVGRAD (XYZ, C, NC, SLATE(11)) | |
93 | TT2 = SLATE(11)**2 + SLATE(12)**2 + SLATE(13)**2 | |
94 | SLATE(14) = (TT2+4.*AA*ABS(CC)) | |
95 | IF (SLATE(14)-TT2.LE.0.1*TT2) THEN | |
96 | SLATE(15) = SQRT(SLATE(14)) | |
97 | SLATE(14) = SLATE(15) | |
98 | ELSE | |
99 | SLATE(15) = SQRT(TT2) | |
100 | SLATE(14) = 0.5*(SLATE(15) + SQRT(SLATE(14))) | |
101 | ENDIF | |
102 | IF (ABS(SLATE(14)).LE.0.) SLATE(14) = 1.E-10 | |
103 | CC = CC / SLATE(14) | |
104 | ||
105 | 999 GVSAFE = CC | |
106 | ||
107 | END |