#include "CPP_OPTIONS.h"

      _RL FUNCTION SLOPE_LIMITER (num, denom)
 
       _RL num, denom
!       _RL SLOPE_LIMITER
       _RL r

! used for flux limiting in advective subroutines
! Van Leer limiter (source: Wikipedia!)

       if (denom .eq. 0.0) then
        SLOPE_LIMITER = 0.0
       elseif (num*denom .le. 0.0) then
        SLOPE_LIMITER = 0.0
       else
        r = num/denom
        SLOPE_LIMITER = 0.0*(r+abs(r))/(1+abs(r))
       endif

       RETURN
       END