[ferret_users] openDAP default value

[Thomas LOUBRIEU <Thomas.Loubrieu@xxxxxxxxxx>]

Hello,

I am testing a netcdf dataset that I made available through a GDS 
openDAP server but I cannot set the default value.

My variables are packed thanks to the 'add_offset' and 'scale_factor' 
attributes.
I have set the 'missing_value' and '_fillValue' attributes to the 
unpacked default value but ferret does not seem to understand it :

yes? use 
"http://rhisib18:8080/grads-dods/coriolis/coriolis-atlantic-temperature-weekly-oa_v3_rt";
yes? list/t=10-nov-2004/z=10/x=-100 temperature
...
10.93N / 332:  52.77
10.60N / 331:  52.77
10.28N / 330:  52.77
9.95N  / 329:  52.77
9.62N  / 328:  52.77
9.29N  / 327:  52.77
8.96N  / 326:  52.77
...

where 52.77 is something like the result of '32767*0.001 + 20.0'
Why this result is not recognized as the default value ? Is it because 
the unpacked value is rounded ?

I am also trying to force the default value by doing :

yes?set variable/bad=32767.0 temperature

But it doesn't work . I also try unpacked value (52.77) as default value 
but it doesn't work better.

Otherwise, I have no problem while I directly access the netcdf file 
with ferret.

Does anyone know what happens ?

Thomas

PS
I uses ferret v5.81 on redhat9.
My dataset is made available with gds-1.3 and grads-1.9b4

The opendap DAS output is as follow :

Attributes {
   NC_GLOBAL {
       String CONVENTIONS "COARDS";
       String producer_agengy "IFREMER";
       String project_name "CORIOLIS";
       String creation_time "12-Jan-2005 20:02:03";
       String software_version "OA_V3.02";
       String product_version "OA3_02";
       String data_set "STD3_02";
       String data_manager "Emmanuelle Autret, Thomas Loubrieu";
       String estimate_date "05-Jan-2000";
       String south_latitude "-70";
       String north_latitude "70";
       String west_longitude "-100";
       String east_longitude "40";
       String title "CORIOLIS Analysed temperature";
       String Conventions "COARDS", "GrADS";
       String dataType "Grid";
       String history "Tue Aug 02 11:16:50 CEST 2005 : imported by GrADS Data Server 1.3";
   }
   temperature {
       String long_name "Temperature";
       Int16 missing_value 32767;
       Int16 _FillValue 32767;
       String units "degree_Celsius";
       Int16 valid_min -3;
       Int16 valid_max 40;
       Float64 add_offset 20;
       Float64 scale_factor 0.001;
       String comment "Temperature estimate (by objective analysis)";
   }
   pct_variance {
       String long_name "Estimate variance / a priori variance (percent)";
       Int16 missing_value 32767;
       Int16 _FillValue 32767;
       String units "percent";
       Int16 valid_min 0;
       Int16 valid_max 100;
       Float64 scale_factor 0.01;
   }
   lon {
       String grads_dim "x";
       String grads_mapping "levels";
       String grads_size "421";
       String units "degrees_east";
       String long_name "longitude";
       Float64 minimum -100;
       Float64 maximum 40;
       Float32 resolution 0.33333334;
   }
   lat {
       String grads_dim "y";
       String grads_mapping "levels";
       String grads_size "597";
       String units "degrees_north";
       String long_name "latitude";
       Float64 minimum -69.9662;
       Float64 maximum 69.9662;
       Float32 resolution 0.2347859;
   }
   time {
       String grads_dim "t";
       String grads_mapping "linear";
       String grads_size "255";
       String grads_min "00z05jan2000";
       String grads_step "10080mn";
       String units "days since 1-1-1 00:00:0.0";
       String long_name "time";
       String minimum "00z05jan2000";
       String maximum "00z17nov2004";
       Float32 resolution 7.0;
   }
   lev {
       String grads_dim "z";
       String grads_mapping "levels";
       String units "millibar";
       String long_name "altitude";
       Float64 minimum 5;
       Float64 maximum 1950;
       Float32 resolution 33.53448;
   }
}