[las_users] Ferret script to return the log of a variable

[Todd Viola <toddviola@xxxxxxxxxxxxxx>]

Hello all, 

I'm trying to solve a simple problem, but I'm afraid I don't have enough 
experience with Ferret scripting to see where I'm going wrong. 

I want to display maps and graphs showing the log of my variable (in this 
case, monthly averaged chlorophyll a), rather than the original variable 
itself. I've been trying to follow the directions on the two pages below, but 
keep getting syntax errors.

http://ferret.pmel.noaa.gov/LAS/documentation/installer-documentation/advanced-dataset-configuration/using-init_scripts-for-custom-ferret-behavior
http://ferret.pmel.noaa.gov/FERRET_17sep07/LAS/FAQ/virtual_variables.html

Here's the relevant snippet from my LAS variable XML:

          <chlamday name="Chlorophyll a monthly" units="mg m^-3" 
url="http://oceanwatch.pfeg.noaa.gov/thredds/dodsC/satellite/SW/chla/mday#SWchla";>
           <link match="/lasdata/grids/SW_mday_grid"/>
           <properties>
            <ferret>
             <fill_type>fill</fill_type>
             <do_contour>0</do_contour>
            </ferret>
           </properties>
          </chlamday>
          <logchlamday name="Log of Chlorophyll a monthly" units="log, mg 
m^-3" 
url="http://oceanwatch.pfeg.noaa.gov/thredds/dodsC/satellite/SW/chla/mday#SWchla";>
           <link match="/lasdata/grids/SW_mday_grid"/>
           <properties>
            <ferret>
             <init_script>chlamday-log.jnl</init_script>             
             <fill_type>fill</fill_type>
             <do_contour>0</do_contour>
            </ferret>
           </properties>
          </logchlamday>

And here is the chlamday-log.jnl script I'm trying to use:

SET DATA ($data_url) 
LET/TITLE="log( Chlorophyll a, mg m^-3 )" logchlamday = log(SWchla)

I'd appreciate any help.

Thanks,
Todd

-- 
Todd Viola
office: +1 361-749-2472
toddviola@xxxxxxxxxxxxxx