gasdevlux.f90 2.88 KB
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!***********************************************************************
!* Copyright 2012,2013                                                *
!* Jerome Brioude, Delia Arnold, Andreas Stohl, Wayne Angevine,       *
!* John Burkhart, Massimo Cassiani, Adam Dingwell, Richard C Easter, Sabine Eckhardt,*
!* Stephanie Evan, Jerome D Fast, Don Morton, Ignacio Pisso,          *
!* Petra Seibert, Gerard Wotawa, Caroline Forster, Harald Sodemann,   *
!* This file is part of FLEXPART WRF                                   *
!*                                                                     *
!* FLEXPART is free software: you can redistribute it and/or modify    *
!* it under the terms of the GNU General Public License as published by*
!* the Free Software Foundation, either version 3 of the License, or   *
!* (at your option) any later version.                                 *
!*                                                                     *
!* FLEXPART is distributed in the hope that it will be useful,         *
!* but WITHOUT ANY WARRANTY; without even the implied warranty of      *
!* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the       *
!* GNU General Public License for more details.                        *
!*                                                                     *
!* You should have received a copy of the GNU General Public License   *
!* along with FLEXPART.  If not, see <http://www.gnu.org/licenses/>.   *
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!***********************************************************************
    !C--- adapted from press et al. 1992 numerial recipes in Fortran by Massimo Cassiani to jse RANLUX as uniform random number generator
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      FUNCTION gasdevlux()
      USE luxury
      INTEGER idum
      REAL gasdevlux     
      INTEGER iset
      REAL fac,gset,rsq,v1,v2,RTEST(2)
      SAVE iset,gset
      DATA iset/0/
      if (iset.eq.0) then
1      call RANLUX(RTEST,2)

        v1=2.*RTEST(1)-1.
        v2=2.*RTEST(2)-1.
        rsq=v1**2+v2**2
        if(rsq.ge.1..or.rsq.eq.0.)goto 1
        fac=sqrt(-2.*log(rsq)/rsq)
        gset=v1*fac
        gasdevlux=v2*fac
        iset=1
      else
        gasdevlux=gset
        iset=0
      endif
      return
      END
      
      subroutine gasdevlux2R(random1,random2)
      USE luxury
      INTEGER idum
      REAL random1,random2      
      INTEGER iset
      REAL fac,gset,rsq,v1,v2,RTEST(2)
      
1      call RANLUX(RTEST,2)

        v1=2.*RTEST(1)-1.
        v2=2.*RTEST(2)-1.
        rsq=v1**2+v2**2
        if(rsq.ge.1..or.rsq.eq.0.)goto 1
        fac=sqrt(-2.*log(rsq)/rsq)
        random1=v1*fac
        random2=v2*fac
  ! Limit the random numbers to lie within the interval -4 and +4
  !**************************************************************
       if (random1.lt.-4.) random1=-4.
       if (random2.lt.-4.) random2=-4.
       if (random1.gt.4.) random1=4.
       if (random2.gt.4.) random2=4.
      return
      END