| 1 | !********************************************************************** |
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| 2 | ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010 * |
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| 3 | ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa, * |
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| 4 | ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann * |
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| 5 | ! * |
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| 6 | ! This file is part of FLEXPART. * |
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| 7 | ! * |
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| 8 | ! FLEXPART is free software: you can redistribute it and/or modify * |
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| 9 | ! it under the terms of the GNU General Public License as published by* |
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| 10 | ! the Free Software Foundation, either version 3 of the License, or * |
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| 11 | ! (at your option) any later version. * |
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| 12 | ! * |
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| 13 | ! FLEXPART is distributed in the hope that it will be useful, * |
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| 14 | ! but WITHOUT ANY WARRANTY; without even the implied warranty of * |
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| 15 | ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
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| 16 | ! GNU General Public License for more details. * |
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| 17 | ! * |
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| 18 | ! You should have received a copy of the GNU General Public License * |
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| 19 | ! along with FLEXPART. If not, see <http://www.gnu.org/licenses/>. * |
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| 20 | !********************************************************************** |
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| 21 | |
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| 22 | ! Taken from Press et al., Numerical Recipes |
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| 23 | |
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| 24 | function ran1(idum) |
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| 25 | |
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| 26 | implicit none |
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| 27 | |
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| 28 | integer :: idum |
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| 29 | real :: ran1 |
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| 30 | integer,parameter :: ia=16807, im=2147483647, iq=127773, ir=2836 |
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| 31 | integer,parameter :: ntab=32, ndiv=1+(im-1)/ntab |
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| 32 | real,parameter :: am=1./im, eps=1.2e-7, rnmx=1.-eps |
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| 33 | integer :: j, k |
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| 34 | integer :: iv(ntab) = (/ (0,j=1,ntab) /) |
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| 35 | integer :: iy=0 |
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| 36 | |
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| 37 | if (idum.le.0.or.iy.eq.0) then |
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| 38 | idum=max(-idum,1) |
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| 39 | do j=ntab+8,1,-1 |
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| 40 | k=idum/iq |
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| 41 | idum=ia*(idum-k*iq)-ir*k |
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| 42 | if (idum.lt.0) idum=idum+im |
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| 43 | if (j.le.ntab) iv(j)=idum |
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| 44 | enddo |
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| 45 | iy=iv(1) |
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| 46 | endif |
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| 47 | k=idum/iq |
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| 48 | idum=ia*(idum-k*iq)-ir*k |
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| 49 | if (idum.lt.0) idum=idum+im |
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| 50 | j=1+iy/ndiv |
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| 51 | iy=iv(j) |
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| 52 | iv(j)=idum |
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| 53 | ran1=min(am*iy,rnmx) |
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| 54 | end function ran1 |
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| 55 | |
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| 56 | |
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| 57 | function gasdev(idum) |
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| 58 | |
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| 59 | implicit none |
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| 60 | |
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| 61 | integer :: idum |
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| 62 | real :: gasdev, fac, r, v1, v2 |
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| 63 | integer :: iset = 0 |
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| 64 | real :: gset = 0. |
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| 65 | real, external :: ran3 |
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| 66 | |
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| 67 | if (iset.eq.0) then |
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| 68 | 1 v1=2.*ran3(idum)-1. |
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| 69 | v2=2.*ran3(idum)-1. |
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| 70 | r=v1**2+v2**2 |
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| 71 | if(r.ge.1.0 .or. r.eq.0.0) go to 1 |
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| 72 | fac=sqrt(-2.*log(r)/r) |
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| 73 | gset=v1*fac |
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| 74 | gasdev=v2*fac |
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| 75 | iset=1 |
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| 76 | else |
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| 77 | gasdev=gset |
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| 78 | iset=0 |
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| 79 | endif |
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| 80 | end function gasdev |
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| 81 | |
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| 82 | |
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| 83 | subroutine gasdev1(idum,random1,random2,inext,inextp,ma,iff) |
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| 84 | |
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| 85 | implicit none |
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| 86 | |
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| 87 | integer :: idum |
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| 88 | real :: random1, random2, fac, v1, v2, r |
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| 89 | integer :: inext,inextp,ma(55),iff |
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| 90 | real, external :: ran3 |
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| 91 | |
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| 92 | 1 v1=2.*ran3(idum,inext,inextp,ma,iff)-1. |
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| 93 | v2=2.*ran3(idum,inext,inextp,ma,iff)-1. |
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| 94 | r=v1**2+v2**2 |
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| 95 | if(r.ge.1.0 .or. r.eq.0.0) go to 1 |
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| 96 | fac=sqrt(-2.*log(r)/r) |
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| 97 | random1=v1*fac |
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| 98 | random2=v2*fac |
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| 99 | ! Limit the random numbers to lie within the interval -3 and +3 |
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| 100 | !************************************************************** |
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| 101 | if (random1.lt.-3.) random1=-3. |
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| 102 | if (random2.lt.-3.) random2=-3. |
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| 103 | if (random1.gt.3.) random1=3. |
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| 104 | if (random2.gt.3.) random2=3. |
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| 105 | end subroutine gasdev1 |
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| 106 | |
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| 107 | |
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| 108 | function ran3(idum,inext,inextp,ma,iff) |
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| 109 | |
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| 110 | implicit none |
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| 111 | |
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| 112 | integer :: idum |
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| 113 | real :: ran3 |
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| 114 | |
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| 115 | integer,parameter :: mbig=1000000000, mseed=161803398, mz=0 |
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| 116 | real,parameter :: fac=1./mbig |
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| 117 | integer :: i,ii,inext,inextp,k |
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| 118 | integer :: mj,mk,ma(55) |
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| 119 | |
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| 120 | ! save inext,inextp,ma |
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| 121 | integer :: iff |
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| 122 | |
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| 123 | if(idum.lt.0.or.iff.eq.0)then |
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| 124 | iff=1 |
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| 125 | mj=mseed-iabs(idum) |
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| 126 | mj=mod(mj,mbig) |
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| 127 | ma(55)=mj |
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| 128 | mk=1 |
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| 129 | do i=1,54 |
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| 130 | ii=mod(21*i,55) |
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| 131 | ma(ii)=mk |
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| 132 | mk=mj-mk |
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| 133 | if(mk.lt.mz)mk=mk+mbig |
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| 134 | mj=ma(ii) |
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| 135 | end do |
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| 136 | do k=1,4 |
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| 137 | do i=1,55 |
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| 138 | ma(i)=ma(i)-ma(1+mod(i+30,55)) |
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| 139 | if(ma(i).lt.mz) ma(i)=ma(i)+mbig |
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| 140 | end do |
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| 141 | end do |
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| 142 | inext=0 |
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| 143 | inextp=31 |
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| 144 | idum=1 |
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| 145 | endif |
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| 146 | inext=inext+1 |
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| 147 | if(inext.eq.56)inext=1 |
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| 148 | inextp=inextp+1 |
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| 149 | if(inextp.eq.56)inextp=1 |
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| 150 | mj=ma(inext)-ma(inextp) |
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| 151 | if(mj.lt.mz)mj=mj+mbig |
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| 152 | ma(inext)=mj |
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| 153 | ran3=mj*fac |
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| 154 | end function ran3 |
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| 155 | ! (C) Copr. 1986-92 Numerical Recipes Software US. |
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