blob: 9a79cb6c08ebc1172cf7922436e45e04075839a6 (
plain) (
blame)
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
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
#include "config.h"
REAL FUNCTION sla_RANDOM (SEED)
*+
* - - - - - - -
* R A N D O M
* - - - - - - -
*
* Generate pseudo-random real number in the range 0 <= X < 1.
* (single precision)
*
*
* Given:
* SEED real an arbitrary real number
*
* Notes:
*
* 1) The result is a pseudo-random REAL number in the range
* 0 <= sla_RANDOM < 1.
*
* 2) SEED is used first time through only.
*
* Called: RAN or RAND (a REAL function returning a random variate --
* the precise function which is called depends on which functions
* are available when the library is built). If neither of these
* is available, we use the local substitute RANDOM defined
* in rtl_random.c
*
* P.T.Wallace Starlink 14 October 1991
*
* 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
*-
IMPLICIT NONE
REAL SEED
#if HAVE_RAND
REAL RAND
#elif HAVE_RANDOM
REAL RANDOM
#else
error "Can't find random-number function"
#endif
REAL AS
INTEGER ISEED
LOGICAL FIRST
SAVE FIRST
DATA FIRST /.TRUE./
* If first time, turn SEED into a large, odd integer
IF (FIRST) THEN
AS=ABS(SEED)+1.0
ISEED=NINT(AS/10.0**(NINT(ALOG10(AS))-6))
IF (MOD(ISEED,2).EQ.0) ISEED=ISEED+1
FIRST=.FALSE.
#if HAVE_RAND
AS = RAND(ISEED)
#endif
ELSE
ISEED=0
END IF
* Next pseudo-random number
#if HAVE_RAND
sla_RANDOM=RAND(0)
#elif HAVE_RANDOM
sla_RANDOM=RANDOM(ISEED)
#endif
END
|
