Re: Problems about ferret command "set axis/modulo "

[Jonathan Callahan <Jonathan.S.Callahan@xxxxxxxx>]

Chi,

As Olivier pointed out, several folks have commented out the line in Ferret.pl that issues the
'set axis/modulo' command.  Recent versions of Ferret can now handle the concept of subspan
modulo axes:

http://ferret.pmel.noaa.gov/Ferret/Documentation/Release_Notes/v550.html#subspan modulo

so the 'set axis/modulo' in LAS probably causes more problems than it solves.

I have a number of small LAS patches/cleanup projects that I will be getting to in July.
Removing 'set axis/modulo' and dealing with whatever problems that causes is one of them.  I'm
hopeful we'll have another beta release of LAS near the end of the summer/beginning of fall.


-- Jon


Chi wrote:

> Hi Jonathan and everyone
>    I found a problem with ferret command "set axis/modulo". I have a 3D netcdf file,
> the longitude are west and are defined as
>     longitude = -30, -29.5, -29, -28.5, -28, -27.5, -27;
>    If I don't use "set axis/modulo" command, just set region using
> set region/x="-27.5"/y="6.5":"11"/z="-200":"-1"/l=1, then everything is fine
>    However, I found that the LAS generated ferret script called
> set axis/modulo to setup longitude as modulo, then it used
> set region/x="332.5"/y="6.5":"11"/z="-200":"-1"/l=1, but it didn't return the
> correct data/image at the longitude -27.5, which is what I needed.
>    I remembered that some perl source code of LAS said that since ferret won't process
> negative west longitude well, then LAS automatically convert it to positive east-wise
> value. However when I manually called ferret script to process my data using negative
> west longitude, everything was fine. It was the "set axis/modulo" command who caused
> me problems.
>    Anybody can help me about this? Or How can I configure LAS not to use "sex axis/modulo"?
>    Thanks a lot, Ding
>
>