source: palm/trunk/SOURCE/random_function.f90 @ 1092

Last change on this file since 1092 was 1092, checked in by raasch, 9 years ago

unused variables remove from several routines

  • Property svn:keywords set to Id
File size: 3.0 KB
Line 
1 MODULE random_function_mod
2
3!--------------------------------------------------------------------------------!
4! This file is part of PALM.
5!
6! PALM is free software: you can redistribute it and/or modify it under the terms
7! of the GNU General Public License as published by the Free Software Foundation,
8! either version 3 of the License, or (at your option) any later version.
9!
10! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
11! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
12! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
13!
14! You should have received a copy of the GNU General Public License along with
15! PALM. If not, see <http://www.gnu.org/licenses/>.
16!
17! Copyright 1997-2012  Leibniz University Hannover
18!--------------------------------------------------------------------------------!
19!
20! Current revisions:
21! -----------------
22! unused variables removed
23!
24! Former revisions:
25! -----------------
26! $Id: random_function.f90 1092 2013-02-02 11:24:22Z raasch $
27!
28! 1036 2012-10-22 13:43:42Z raasch
29! code put under GPL (PALM 3.9)
30!
31! RCS Log replace by Id keyword, revision history cleaned up
32!
33! Revision 1.3  2003/10/29 09:06:57  raasch
34! Former function changed to a module.
35!
36! Revision 1.1  1998/02/04 16:09:45  raasch
37! Initial revision
38!
39!
40! Description:
41! ------------
42! Random number generator, produces numbers equally distributed in interval [0,1]
43! This routine is taken from the "numerical recipies"
44!------------------------------------------------------------------------------!
45
46    IMPLICIT NONE
47
48    PRIVATE
49
50    PUBLIC random_function, random_function_ini
51
52    INTEGER, PUBLIC, SAVE ::  random_iv(32), random_iy
53
54    INTERFACE random_function_ini
55       MODULE PROCEDURE random_function_ini
56    END INTERFACE random_function_ini
57
58    INTERFACE random_function
59       MODULE PROCEDURE random_function
60    END INTERFACE random_function
61
62 CONTAINS
63
64    SUBROUTINE random_function_ini
65
66       IMPLICIT NONE
67
68       random_iv = 0
69       random_iy = 0
70
71    END SUBROUTINE random_function_ini
72
73    FUNCTION random_function( idum )
74
75
76       IMPLICIT NONE
77
78       INTEGER ::  ia, idum, im, iq, ir, ndiv, ntab
79       REAL    ::  am, eps, random_function, rnmx
80
81       PARAMETER ( ia=16807, im=2147483647, am=1.0/im, iq=127773, ir=2836, &
82                   ntab=32, ndiv=1+(im-1)/ntab, eps=1.2e-7, rnmx=1.0-eps )
83
84       INTEGER ::  j, k
85
86
87       IF ( idum .le. 0  .or.  random_iy .eq. 0 )  THEN
88          idum = max (-idum,1)
89          DO  j = ntab+8,1,-1
90             k    = idum / iq
91             idum = ia * ( idum - k * iq ) - ir * k
92             IF ( idum .lt. 0 )  idum = idum + im
93             IF ( j .le. ntab )  random_iv(j) = idum
94          ENDDO
95          random_iy = random_iv(1)
96       ENDIF
97
98       k    = idum / iq
99       idum = ia * ( idum - k * iq ) - ir * k
100       IF ( idum .lt. 0 )  idum = idum + im
101       j            = 1 + random_iy / ndiv
102       random_iy    = random_iv(j)
103       random_iv(j) = idum
104       random_function  = min ( am * random_iy , rnmx )
105
106    END FUNCTION random_function
107
108 END MODULE random_function_mod
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