2nd resolution Wave_t_ex

[Lin Ji]

  First, thank you for your quick response. I still want to use the 2nd
resolution since it is much faster. But, there is one more thing I want to
clarify. When you say to impose the spatial kind of distribution I want in
the formulation, does it mean I have to define two functions 'dfdt1[]' and
'dfdt2[]' and two formulations for the first two resolutions, one ('Wave_t')
use the 'dfdt1[]' function defined in both time and space, the other
('Wave_t_ex') use the 'dfdt2[]' function defined only in space? In this case,
dfdt1[] would be dfdt2[]*TimeFct[]. Am I right?
  Also if I set the 'Re_Use_ILU' flag to 1, will it affect the accuracy of
the solution? What is the trade off for speed up the computation?
  Finally, if you have time, can you say more about using higher order (2nd
order) interpolation? I guess I must have made some mistake because the
result I get is wildly out of range at the end of the wave propagation. In
the email you tell me how to add the 2nd order interpolation, you mentioned
not to forget specifying the constraint on the 2nd order. Can you tell me how
to do that? What I did is just to copy the constraint 'u' which means no
constraint.

Best wishes,

Lin

-- 
Dept. of Math., RPI
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