CIP method (3)

The values of Q and  are given at
     (i,j,k), (iup,j,k), (i,jup,k), (i,j,kup)

and Q at

     (iup,jup,k), (i,jup,kup)
     (iup,j,kup), (iup,jup,kup)

where

     

The profile between these points can be described by cubic polynomial.