src/equations/cles_dcflag_smooth1d.f

c     xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
c
c                Flux smoothness based detection
c
c     xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

      subroutine cles_dcflag(ux,vx,dcflag,ncomps,nvars,
     $     ixlo,ixhi, nx, dx, direction,extra)

      implicit none

      integer ncomps, nvars
      integer ixlo, ixhi
      integer direction, extra(*)
      INTEGER nx
      integer dcflag(1:nx+1,1)
      double precision ux(ncomps,ixlo:ixhi)
      double precision vx(nvars,ixlo:ixhi)
      DOUBLE PRECISION dx

      integer i, m, slow, shigh, loop, size, enoOrder
      double precision smoothness, dmdx, maxv(4), minv(4), variance(4)
      integer span
      double precision TriggerValue, smooth_eps

      TriggerValue = 0.0d0
      smooth_eps = 0.001
      span = 3

      enoOrder = extra(1)
      size = enoOrder-1
      
      ! ---- test criteria at each point
      DO i = 1, nx+1, 1
         
         DO loop =1,4
            do m=i-size, i+size-1
               dmdx = abs(fx(loop,m+1)-fx(loop,m-1))
               if ( m .eq. i-size ) then
                  maxv(loop) = dmdx
                  minv(loop) = dmdx
               else
                  maxv(loop) = MAX(maxv(loop), dmdx)
                  minv(loop) = MIN(minv(loop), dmdx)
               endif
            enddo
            variance(loop) = maxv(loop)/(minv(loop)+smooth_eps)
            if ( loop .eq. 1 ) then
               smoothness = variance(loop)
            else
               smoothness = MAX(smoothness, variance(loop))
            endif
         END DO
         
         IF ( smoothness .gt. TriggerValue ) THEN
         
             ! we are at a shock
             ! ---- we will use WENO here
            slow = max(i-span,1)
            shigh = min(i+span,nx+1)
            do m=slow,shigh
               dcflag(m,direction) = 1
            enddo
         END IF
         
      END DO

      return
      end

<