source: palm/tags/release-3.8/SOURCE/random_gauss.f90 @ 4343

Last change on this file since 4343 was 484, checked in by raasch, 11 years ago

typo in file headers removed

  • Property svn:keywords set to Id
File size: 1.6 KB
Line 
1 FUNCTION random_gauss( idum, upper_limit )
2
3!------------------------------------------------------------------------------!
4! Current revisions:
5! -----------------
6!
7!
8! Former revisions:
9! -----------------
10! $Id: random_gauss.f90 484 2010-02-05 07:36:54Z oliver.maas $
11! RCS Log replace by Id keyword, revision history cleaned up
12!
13! Revision 1.4  2006/08/04 15:01:48  raasch
14! Range of random number is limited by an upper limit (new second parameter)
15!
16! Revision 1.1  1998/03/25 20:09:47  raasch
17! Initial revision
18!
19!
20! Description:
21! ------------
22! Generates a gaussian distributed random number (mean value 1, sigma = 1)
23! This routine is taken from the "numerical recipies".
24!------------------------------------------------------------------------------!
25
26    USE random_function_mod
27
28    IMPLICIT NONE
29
30    INTEGER :: idum, iset
31    REAL    :: fac, gset, random_gauss, rsq, upper_limit, v1, v2
32
33    SAVE  iset, gset
34
35    DATA  iset /0/
36
37!
38!-- Random numbers are created as long as they do not fall below the given
39!-- upper limit
40    DO
41
42       IF ( iset == 0 )  THEN
43          rsq = 0.0
44          DO  WHILE ( rsq >= 1.0  .OR.  rsq == 0.0 )
45             v1  = 2.0 * random_function( idum ) - 1.0
46             v2  = 2.0 * random_function( idum ) - 1.0
47             rsq = v1**2 + v2**2
48          ENDDO
49          fac          = SQRT( -2.0 * LOG( rsq ) / rsq )
50          gset         = v1 * fac
51          random_gauss = v2 * fac + 1.0
52          iset         = 1
53       ELSE
54          random_gauss = gset + 1.0
55          iset         = 0
56       ENDIF
57
58       IF ( ABS( random_gauss - 1.0 ) <= upper_limit )  EXIT
59
60    ENDDO
61
62 END FUNCTION random_gauss
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