c     kspectrum (http://www.meso-star.com/en_Products.html) - This file is part of kspectrum
c     Copyright (C) 2008-2015 - Méso-Star - Vincent Eymet
c     
c     This file must be used under the terms of the CeCILL license.
c     This source file is licensed as described in the file COPYING, which
c     you should have received as part of this distribution.  The terms
c     are also available at
c     http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
c     
      subroutine ssort(l)
      implicit none
      include 'max.inc'
      include 'arrays3.inc'
c
c     Purpose: to sort input array "a" by increasing values of a(1,*)
c
c     Inputs:
c       + a: input data array, l lines by nc columns
c       + l: number of lines
c     
c     Outputs:
c       + a: data array, sorted by increasing values of a(1,*)
c
c     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
c     Routine extracted from file "bmatch.f" found on Google Code Search,
c     from the work of:
c             Micali, S. and Vazirani, V. V.,"An O(square root of V * E)
c             Algorithm for Finding Maximum Matching in General Graphs",
c             Proc. 21st Annual Symposium on Foundation of Computer
c             Science, IEEE, 1980, pp. 17-27.
c
c     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      integer l,f,n2,s,t,ls,i,is,j,js,jj
      double precision bh,tmp(1:2)
c - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      do i=1,l
         b(i)=i
      enddo
      f=1
      if (l.le.f) return
      n2=(l-f+1)/2
      s=1023
      do 100 t=1,10
      if (s.gt.n2) goto 90
      ls=l-s
      do 20 i=f,ls
      is=i+s
      do jj=1,2
         tmp(jj)=a(is,jj)
      enddo
      bh=b(is)
      j=i
      js=is
    5 if (tmp(1).ge.a(j,1)) goto 10
      do jj=1,2
         a(js,jj)=a(j,jj)
      enddo
      b(js)=b(j)
      js=j
      j=j-s
      if (j.ge.f) goto 5
 10   continue
      do jj=1,2
         a(js,jj)=tmp(jj)
      enddo
      b(js)=bh
   20 continue
   90 s=s/2
  100 continue
      return
      end