[1] | 1 | MODULE random_function_mod |
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[1036] | 2 | |
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| 3 | !--------------------------------------------------------------------------------! |
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| 4 | ! This file is part of PALM. |
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| 5 | ! |
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| 6 | ! PALM is free software: you can redistribute it and/or modify it under the terms |
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| 7 | ! of the GNU General Public License as published by the Free Software Foundation, |
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| 8 | ! either version 3 of the License, or (at your option) any later version. |
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| 9 | ! |
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| 10 | ! PALM is distributed in the hope that it will be useful, but WITHOUT ANY |
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| 11 | ! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR |
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| 12 | ! A PARTICULAR PURPOSE. See the GNU General Public License for more details. |
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| 13 | ! |
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| 14 | ! You should have received a copy of the GNU General Public License along with |
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| 15 | ! PALM. If not, see <http://www.gnu.org/licenses/>. |
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| 16 | ! |
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[1310] | 17 | ! Copyright 1997-2014 Leibniz Universitaet Hannover |
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[1036] | 18 | !--------------------------------------------------------------------------------! |
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| 19 | ! |
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[484] | 20 | ! Current revisions: |
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[1] | 21 | ! ----------------- |
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[1093] | 22 | ! |
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[1] | 23 | ! |
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| 24 | ! Former revisions: |
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| 25 | ! ----------------- |
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[3] | 26 | ! $Id: random_function.f90 1310 2014-03-14 08:01:56Z raasch $ |
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[1037] | 27 | ! |
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[1093] | 28 | ! 1092 2013-02-02 11:24:22Z raasch |
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| 29 | ! unused variables removed |
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| 30 | ! |
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[1037] | 31 | ! 1036 2012-10-22 13:43:42Z raasch |
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| 32 | ! code put under GPL (PALM 3.9) |
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| 33 | ! |
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[3] | 34 | ! RCS Log replace by Id keyword, revision history cleaned up |
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| 35 | ! |
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[1] | 36 | ! Revision 1.3 2003/10/29 09:06:57 raasch |
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| 37 | ! Former function changed to a module. |
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| 38 | ! |
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| 39 | ! Revision 1.1 1998/02/04 16:09:45 raasch |
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| 40 | ! Initial revision |
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| 41 | ! |
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| 42 | ! |
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| 43 | ! Description: |
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| 44 | ! ------------ |
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| 45 | ! Random number generator, produces numbers equally distributed in interval [0,1] |
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| 46 | ! This routine is taken from the "numerical recipies" |
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[3] | 47 | !------------------------------------------------------------------------------! |
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[1] | 48 | |
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| 49 | IMPLICIT NONE |
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| 50 | |
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| 51 | PRIVATE |
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| 52 | |
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| 53 | PUBLIC random_function, random_function_ini |
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| 54 | |
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| 55 | INTEGER, PUBLIC, SAVE :: random_iv(32), random_iy |
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| 56 | |
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| 57 | INTERFACE random_function_ini |
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| 58 | MODULE PROCEDURE random_function_ini |
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| 59 | END INTERFACE random_function_ini |
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| 60 | |
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| 61 | INTERFACE random_function |
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| 62 | MODULE PROCEDURE random_function |
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| 63 | END INTERFACE random_function |
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| 64 | |
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| 65 | CONTAINS |
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| 66 | |
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| 67 | SUBROUTINE random_function_ini |
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| 68 | |
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| 69 | IMPLICIT NONE |
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| 70 | |
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| 71 | random_iv = 0 |
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| 72 | random_iy = 0 |
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| 73 | |
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| 74 | END SUBROUTINE random_function_ini |
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| 75 | |
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| 76 | FUNCTION random_function( idum ) |
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| 77 | |
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| 78 | |
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| 79 | IMPLICIT NONE |
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| 80 | |
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| 81 | INTEGER :: ia, idum, im, iq, ir, ndiv, ntab |
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[1092] | 82 | REAL :: am, eps, random_function, rnmx |
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[1] | 83 | |
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| 84 | PARAMETER ( ia=16807, im=2147483647, am=1.0/im, iq=127773, ir=2836, & |
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| 85 | ntab=32, ndiv=1+(im-1)/ntab, eps=1.2e-7, rnmx=1.0-eps ) |
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| 86 | |
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| 87 | INTEGER :: j, k |
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| 88 | |
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| 89 | |
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| 90 | IF ( idum .le. 0 .or. random_iy .eq. 0 ) THEN |
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| 91 | idum = max (-idum,1) |
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| 92 | DO j = ntab+8,1,-1 |
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| 93 | k = idum / iq |
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| 94 | idum = ia * ( idum - k * iq ) - ir * k |
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| 95 | IF ( idum .lt. 0 ) idum = idum + im |
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| 96 | IF ( j .le. ntab ) random_iv(j) = idum |
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| 97 | ENDDO |
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| 98 | random_iy = random_iv(1) |
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| 99 | ENDIF |
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| 100 | |
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| 101 | k = idum / iq |
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| 102 | idum = ia * ( idum - k * iq ) - ir * k |
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| 103 | IF ( idum .lt. 0 ) idum = idum + im |
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| 104 | j = 1 + random_iy / ndiv |
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| 105 | random_iy = random_iv(j) |
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| 106 | random_iv(j) = idum |
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| 107 | random_function = min ( am * random_iy , rnmx ) |
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| 108 | |
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| 109 | END FUNCTION random_function |
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| 110 | |
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| 111 | END MODULE random_function_mod |
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