irregular grid

[Thierry Philipovitch <thierry@xxxxxxxxxxxxxx>]

Hello,
I'm currently using ferret v4.91 under Linux.
I'm trying to plot the variable named elev stored in a netcdf file with
the cdl description given at the end of this message.
on ferret prompt, when I tried 'use mbathy.nc' I received this curious
message:
yes? use mbathy.nc
 *** Unknown error code:       500 ***
             Expected: lon Found: not a 1D variable
Subscript 1 of DS_DES_NAME (value 0) is out of range (1:30)
Program terminated by fatal error
Abort (core dumped)        

Is there someone who could tell me what the problem is ?

Note:I guess the problem is related to the bidimensionnality of axe
variables lon/lat, but I believed that version 4.91 of ferret could
manage this. I can figure out why this is not the case.

Thanks a lot in advance !
Thierry

Here's the cdl descp. of the file:

netcdf mbathy {
dimensions:
        lon = 200 ;
        lat = 150 ;
variables:
        double lon(lon, lat) ;
                lon:name = "lon" ;
                lon:long_name = "LONGITUDE" ;
                lon:generic_name = "lon" ;
                lon:units = "degree_east" ;
        double lat(lon, lat) ;
                lat:name = "lat" ;
                lat:long_name = "LATITUDE" ;
                lat:generic_name = "lat" ;
                lat:units = "degree_north" ;
        double easternlon(lon, lat) ;
                easternlon:name = "easternlon" ;
                easternlon:long_name = "LONGITUDE OF EASTERN SIDE" ;
                easternlon:generic_name = "lon" ;
                easternlon:units = "degree_east" ;
        double northernlat(lon, lat) ;
                northernlat:name = "northernlat" ;
                northernlat:long_name = "LATITUDE OF NORTHEN SIDE" ;
                northernlat:generic_name = "lat" ;
                northernlat:units = "degree_north" ;
        double elev(lon, lat) ;
                elev:name = "elev" ;
                elev:long_name = "ELEVATION" ;
                elev:units = "m" ;
                elev:positive = "up" ;
        double elev_east(lon, lat) ;
                elev_east:name = "elev_east" ;
                elev_east:long_name = "ELEVATION OF EASTERN SIDE" ;
                elev_east:units = "m" ;
                elev_east:positive = "up" ;
        double elev_north(lon, lat) ;
                elev_north:name = "elev_north" ;
                elev_north:long_name = "ELEVATION OF NORTHERN SIDE" ;
                elev_north:units = "m" ;
                elev_north:positive = "up" ;

// global attributes:
                :CREATION_DATE = "1999-01-27 15:38:33" ;
                :history = "created on 1999-01-27 15:38:33" ;
                :author = "Thierry Philipovitch" ;
                :Source = "SAFEGE CETIIS" ;          
-- 
Thierry Philipovitch              Thierry.Philipovitch@cetiis.fr
SAFEGE-CETIIS                          Tel. : (33) 4 42 93 65 17
Aix Metropole Bt D/30, av Malacrida    Fax  : (33) 4 42 93 65 15
FR 13100 Aix-en-Provence