vertical cdiff

[Maisa Rojas Corradi]

Hello there,
I am trying to use the grads CDIFF function with the vertical dimension
but get following error message:

ga-> define ugrad0k=cdiff(ua.1,z)
Error from CDIFF:  Specified dimension non varying
Operation Error:  Error from cdiff function
  Error ocurred at column 1


I have, of course set the z dimension varying before...is there something
special to do with Z ?????

many thanks,
Maisa


*******************************
ga-> sdfopen ua_SE_0k_ccsm.nc
Scanning self-describing file:  ua_SE_0k_ccsm.nc
SDF:  The double precision values of the variable lon_bnds
will be automatically converted to single precision.
SDF:  The double precision values of the variable lat_bnds
will be automatically converted to single precision.
SDF file ua_SE_0k_ccsm.nc is open as file 1
LON set to 0 360
LAT set to -87.8638 87.8638
LEV set to 100000 100000
Time values set: 355:4:21:0 355:4:21:0
ga-> set z 1 14
LEV set to 100000 5000
ga-> define ugrad0k=cdiff(ua.1,z)
Error from CDIFF:  Specified dimension non varying
Operation Error:  Error from cdiff function
  Error ocurred at column 1
DEFINE error:  Invalid expression.


--
Maisa Rojas Corradi
Departamento de Geofisica
Universidad de Chile
Blanco Encalada 2002
Tel: 978 43 00