[ferret_users] question about @iin

[yangxing zheng <yangxingz@xxxxxxxxx>]

Hi,

   I do have a question about indefinite integral in
ferret. The question is what is result of the first
and end grid point? For example,

   if I have a point data of w (vertical velocity in
the ocean) only a function of depth
(z=0,5,15,15,23,30,36,...450,500)

   If the first result of w[z=@iin] is at first grid
point (i.e., z=0)? The last value is at z=500? I list
the value of w[z=@iin], and there is a value at k=1(or
z=0), but  I am not quite sure if  w[z=0:0@din] is the
first value of w[z=@iin].

   Ferret user guide says: "The result of the
indefinite integral is shifted by 1/2 of a grid cell
from its "proper" location. This is because the result
at each grid cell includes the integral computed to
the upper end of that cell. (This was necessary in
order that var[I=lo:hi@DIN] and var[I=lo:hi@IIN]
produce consistent results." I don't really understand
this statement.

  If the first value of w[z=@iin] is not actually at
z=0, then how can we correct it?


  Thanks a lot!

  Yangxing


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