1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
SUBROUTINE slDVN (V, UV, VM)
*+
* - - - -
* D V N
* - - - -
*
* Normalizes a 3-vector also giving the modulus (double precision)
*
* Given:
* V d(3) vector
*
* Returned:
* UV d(3) unit vector in direction of V
* VM d modulus of V
*
* Notes:
*
* 1 If the modulus of V is zero, UV is set to zero as well.
*
* 2 To comply with the ANSI Fortran 77 standard, V and UV must be
* different arrays. However, the routine is coded so as to work
* properly on most platforms even if this rule is violated.
*
* Last revision: 22 July 2004
*
* Copyright P.T.Wallace. All rights reserved.
*
* License:
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see SLA_CONDITIONS); if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*
* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
*-
IMPLICIT NONE
DOUBLE PRECISION V(3),UV(3),VM
INTEGER I
DOUBLE PRECISION W1,W2
* Modulus.
W1 = 0D0
DO I=1,3
W2 = V(I)
W1 = W1+W2*W2
END DO
W1 = SQRT(W1)
VM = W1
* Normalize the vector.
IF (W1.LE.0D0) W1 = 1D0
DO I=1,3
UV(I) = V(I)/W1
END DO
END
|
