cdiff

[Davide Sacchetti]

if you are computing SST using aave or similars X and Y may be
varying ...

first solution:
set x 1 20 (I'm inventing)
set y 1 30
set t 1 last
set z 1
define SSTdef=aave(SST,g)
set x 1
set y 1
d cdiff(SSTdef,t)

second solution:
display (SST(t+1) - SST(t-1))/2

hoping it helps ...
bye bye
Davide

On Thu, 2008-06-19 at 19:18 +0630, S.Amin wrote:
> Dear all
>    I wish to use grads function- cdiff for calculating
> centered difference in time dimension. All other
> 3 dimensions (x,y and z) are not varying (fixed) as
> it is to be calaculated for Sea surface temperature
> averaged over North Bay of Bengal. since it
> is SST, z is not varying and region averaged
> so x and y are also fixed. I have given time
> varying but error is
> Error from CDIFF:  Specified dimension non varying
> Operation Error:  Error from cdiff function
>   Error ocurred at column 1
> DEFINE error:  Invalid expression.
>
> I noticed similar error for z dimension in grads
> user archive.
> Can anybody help to solve this problem?
> Sujata Mandke
> Scientist,Climate and Global Modeling Division
> Indian Institute of Tropical Meteorology
> PUNE,INDIA.
>
>
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> Open WebMail Project (http://openwebmail.org)
>
--
Sacchetti Davide
ARPAL UO3 Centro Meteo Idrologico Regione Liguria - Dir. Scientifica
V.le Brigare Partigiane 2 16121 Genova (I)
tel: +39 010 6437535
mail: davide.sacchetti at arpal.org   web: www.meteoliguria.it