Computing Derivatives

[Steve Guimond <guimond@xxxxxxxxxxxxx>]

Hello:
   I need to compute vorticity over a certain domain and want to know the 
best way to do 
this in ferret.  My data looks like this:

U  I=1:121   J=1:91   L=1:15
V  I=1:121   J=1:91   L=1:15

I have been using this command:

let dvdx = u[I=1,J=50,L=1] - u[I=2,J=50,L=1]

I just need to know how to run a loop through all the longitudes to
compute dv/dx so that I 
don't have to do this for each point and can access them for the
calculation of vorticity.  Any 
help would be appreciated.

Thanks.


Stephen R. Guimond        
Graduate Research Assistant
Center for Ocean-Atmospheric Prediction Studies