c     Copyright (C) 2008-2014 Vincent Eymet
c
c     KDISTRIBUTION is free software; you can redistribute it and/or modify
c     it under the terms of the GNU General Public License as published by
c     the Free Software Foundation; either version 3, or (at your option)
c     any later version.

c     KDISTRIBUTION is distributed in the hope that it will be useful,
c     but WITHOUT ANY WARRANTY; without even the implied warranty of
c     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
c     GNU General Public License for more details.

c     You should have received a copy of the GNU General Public License
c     along with KDISTRIBUTION; if not, see <http://www.gnu.org/licenses/>
c
      subroutine sort_gw(n,g,w)
      implicit none
      include 'max.inc'
c
c     Purpose: to sort "g" and "w" arrays by ascending order of "g"
c     
c     Inputs:
c       + n: number of points in "g" and "w" arrays
c
c     I/O:
c       + g: array of "n" values of "g"
c       + w: array of "n" values of "w"
c
      integer n,i,j,f(Nqmx),p
      double precision g(Nqmx),w(Nqmx)
      double precision g_in(Nqmx),w_in(Nqmx)
      double precision g_out(Nqmx),w_out(Nqmx)
      double precision min
c     label
      integer strlen
      character*(Nchar_mx) label
      label='subroutine sort_gw'

      do i=1,n
         g_in(i)=g(i)
         w_in(i)=w(i)
      enddo

      do i=1,n
         f(i)=0
      enddo
      
c     Debug
c      write(*,*) 'This is sort_gw'
c      do i=1,n
c         write(*,*) 'g(',i,')=',g(i),' w(',i,')=',w(i)
c      enddo
c      write(*,*)
c     Debug
      do i=1,n
c     Debug
c         write(*,*) 'Step number',i
c         do j=1,n
c            write(*,*) 'f(',j,')=',f(j)
c         enddo
c     Debug
         do j=1,n
            if (f(j).ne.1) then
               min=g_in(j)
               p=j
               goto 123
            endif
         enddo
 123     continue
         do j=1,n
            if ((g_in(j).lt.min).and.(f(j).eq.0)) then
               min=g_in(j)
               p=j
            endif
         enddo ! j
c     Debug
c         write(*,*) 'min=',min,' found at p=',p
c     Debug
         g_out(i)=g_in(p)
         w_out(i)=w_in(p)
         f(p)=1
c     Debug
c         write(*,*) 'g_out(',i,')=',g_out(i),' w_out(',i,')=',w_out(i)
c         write(*,*)
c     Debug
      enddo ! i

c     Debug
c      write(*,*) 'Final:'
c      do i=1,n
c         write(*,*) 'g_out(',i,')=',g_out(i),' w_out(',i,')=',w_out(i)
c      enddo
c     Debug
      
      do i=1,n
         g(i)=g_out(i)
         w(i)=w_out(i)
      enddo


      return
      end