[gradsusr] vertical derivative

[Arlindo da Silva]

On Sun, Jun 26, 2011 at 2:43 AM, Shing <midicarcas at gmail.com> wrote:

> hi
>
> i want to take vertical derivative of humidity in the isobaric coordinates.
> i used the function cdiff:
>
>
> define dq=cdiff(q,z)
>
> but got error message saying
> error from cdiff: specific dimension non varying
> operation error: error from cdiff function
> error occurred at column 1
> define error: invalid expression
>
> it works fine when i take horizontal derivatives, such as dq=cdiff(q,x) and
> dq=cdiff(q,y)
>
> is it not the way to do vertical derivative in grads?
>
> thank you very much!
>
>
The opengrads extensions, libbjt (Ben-Jei Tsuang's library), contains a
number of both horizontal and vertical advection functions:

ADVECTION FUNCTIONS<http://opengrads.org/doc/udxt/libbjt/libbjt.html#advection_functions>

By setting the wind to "1" you you be able to get the desired gradient.

   Good Luck,

        Arlindo




> shing
>
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>


-- 
Arlindo da Silva
dasilva at alum.mit.edu
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