composite & derived variables

[Matthew Harrison <mh2@xxxxxxxx>]

Greetings,

I'm using LAS4.0.  It is working as expected for most of what I'm doing,
but I'm encountering some unexpected behavior w/r/t composite variables
and derived variables defined by a ferret script.

First, w/r/t composite variables, i.e. 

    <u units="cm/s" name="Zonal velocity">
     <link match="/lasdata/grids/file_x_y_z_Time_grid"/>
    </u>
    <v units="cm/s" name="Meridional velocity">
     <link match="/lasdata/grids/file_x_y_z_Time_grid"/>
    </v>

   <composite> 
    <current_vectors name="uv_current vectors" js="VecVariable">
       <link match="/file/variables/u"/>
       <link match="/file/variables/v"/>
    </current_vectors>
   </composite>

After making the HTML and Java files, the LAS server does not bring up
the correct z axis menubuttons.  In this case, u and v each have 40
vertical levels show up on the menubuttons, but the composite variable
only brings up 1 level.  It seems that the link elements from the
primary variables u and v are not being delivered to the composite
element current_vectors.  Is this a problem with the LAS software or did
I do something wrong?


************************

Now, w/r/t derived variables defined by a ferret script using the
init_script feature, I'm having a problem of a more serious nature.  I
can define a derived variable easily enough, but when I attempt to do a
difference involving defined variables, I run into trouble.  It appears
from looking at the error logs that the init script is not executed
prior to running the differencing script. Is it possible to check if a
difference variable has a ferret properties tag and call it before the
difference script is executed?

I'll stop here.  Thanks.

Matt

-- 
Matthew J. Harrison	       	                         GFDL
Physical Scientist					 P.O. Box 308
NOAA Geophysical Fluid Dynamics Laboratory               Princeton, NJ
08542
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