source: palm/trunk/SOURCE/random_gauss.f90 @ 4182

Last change on this file since 4182 was 4182, checked in by scharf, 22 months ago
  • corrected "Former revisions" section
  • minor formatting in "Former revisions" section
  • added "Author" section
  • Property svn:keywords set to Id
File size: 2.7 KB
RevLine 
[1682]1!> @file random_gauss.f90
[2000]2!------------------------------------------------------------------------------!
[2696]3! This file is part of the PALM model system.
[1036]4!
[2000]5! PALM is free software: you can redistribute it and/or modify it under the
6! terms of the GNU General Public License as published by the Free Software
7! Foundation, either version 3 of the License, or (at your option) any later
8! version.
[1036]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!
[3655]17! Copyright 1997-2019 Leibniz Universitaet Hannover
[2000]18!------------------------------------------------------------------------------!
[1036]19!
[484]20! Current revisions:
[1]21! -----------------
[1321]22!
[2001]23!
[1321]24! Former revisions:
25! -----------------
26! $Id: random_gauss.f90 4182 2019-08-22 15:20:23Z scharf $
[2716]27! Corrected "Former revisions" section
28!
[4182]29! 3655 2019-01-07 16:51:22Z knoop
30! Corrected "Former revisions" section
[1321]31!
[4182]32! Revision 1.1  1998/03/25 20:09:47  raasch
33! Initial revision
34!
35!
[1]36! Description:
37! ------------
[1682]38!> Generates a gaussian distributed random number (mean value 1, sigma = 1)
39!> This routine is taken from the "numerical recipies".
[1]40!------------------------------------------------------------------------------!
[1682]41 FUNCTION random_gauss( idum, upper_limit )
42 
[1]43
[1320]44    USE kinds
[1]45
[1320]46    USE random_function_mod,                                                   &
47        ONLY:  random_function
48
[1]49    IMPLICIT NONE
50
[1682]51    INTEGER(iwp) ::  idum          !<
52    INTEGER(iwp) ::  iset          !<
[1]53
[1682]54    REAL(wp)     ::  fac           !<
55    REAL(wp)     ::  gset          !<
56    REAL(wp)     ::  random_gauss  !<
57    REAL(wp)     ::  rsq           !<
58    REAL(wp)     ::  upper_limit   !<
59    REAL(wp)     ::  v1            !<
60    REAL(wp)     ::  v2            !<
[1320]61
[1]62    SAVE  iset, gset
63
64    DATA  iset /0/
65
66!
67!-- Random numbers are created as long as they do not fall below the given
68!-- upper limit
69    DO
70
71       IF ( iset == 0 )  THEN
[1342]72          rsq = 0.0_wp
73          DO  WHILE ( rsq >= 1.0_wp  .OR.  rsq == 0.0_wp )
74             v1  = 2.0_wp * random_function( idum ) - 1.0_wp
75             v2  = 2.0_wp * random_function( idum ) - 1.0_wp
[1]76             rsq = v1**2 + v2**2
77          ENDDO
[1342]78          fac          = SQRT( -2.0_wp * LOG( rsq ) / rsq )
[1]79          gset         = v1 * fac
[1342]80          random_gauss = v2 * fac + 1.0_wp
[1]81          iset         = 1
82       ELSE
[1342]83          random_gauss = gset + 1.0_wp
[1]84          iset         = 0
85       ENDIF
86
[1342]87       IF ( ABS( random_gauss - 1.0_wp ) <= upper_limit )  EXIT
[1]88
89    ENDDO
90
91 END FUNCTION random_gauss
Note: See TracBrowser for help on using the repository browser.