subroutine initsl(ncells,fx,lx,ifirst,ilast,
     &  xold)
c     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      double precision roundoff,small,huge,undefind
      common/machine/roundoff,small,huge,undefind
c     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      include "./linearad.i"
c     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      integer ncells,fx,lx,ifirst,ilast
      double precision xold(fx:lx,1:4)

      integer ie, je
      double precision width,velocity
      double precision temp, temp1, temp2
c     ******************************************************************
c     interior values only; others defined by boundary conditions
c     ******************************************************************
      width=statergt-statelft
      if(beta.ne.0.d0) then
         velocity=alpha/beta
      else
         velocity=0.d0
      endif

      width=width/dble(ilast/4-ifirst)
      do ie=ifirst,ilast/4
         xold(ie,1)=statelft+dble(ie)*width
         xold(ie,2)=statergt
         xold(ie,3)=0.d0
         xold(ie,4)=-1.d0
      enddo
      do ie=ilast/4+1,ilast/2
         xold(ie,1)=statergt
         xold(ie,2)=statergt-dble(ie-ilast/4)*width
         xold(ie,3)=-1.d0
         xold(ie,4)=0.d0
      enddo
      do ie=ilast/2+1,ilast*3/4
         xold(ie,1)=statergt-width*dble(ie-ilast/2)
         xold(ie,2)=statelft
         xold(ie,3)=0.d0
         xold(ie,4)=1.d0
      enddo
      do ie=ilast*3/4+1,ilast
         xold(ie,1)=statelft
         xold(ie,2)=statelft+width*dble(ie-ilast*3/4)
         xold(ie,3)=1.d0
         xold(ie,4)=0.d0
      enddo

      open( UNIT=10, FILE='ini.txt')
      do ie=ifirst,ilast
         read(10,*) xold(ie,1), xold(ie,2), xold(ie,3), xold(ie,4)
c         xold(ie,1) = xold(ie,1)*1.666666667d0
c         xold(ie,2) = xold(ie,2)*1.666666667d0
      enddo
      rewind(10)

      return
      end