Re: [ferret_users] question about @iin

["William.S.Kessler" <William.S.Kessler@xxxxxxxx>]

See extensive discussion of @iin in the user group archives. Search  
@iin and look for the message from Steve "How to do @rsum and @iin in  
reverse?". Also see the further reply by Ryo Furue. These do not  
directly answer your question but should shed some light on exactly  
what @iin is doing.

Billy K

On 21/12/2007, at 11:24 AM, yangxing zheng wrote:

> 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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