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Defines dimension names, dimension sizes, unlimited dimensions on a supported file.


	procedure filedimdef (
		thefile       [1] : file,             
		dim_names     [*] : string,           
		dim_sizes     [*] : integer or long,  
		dim_unlimited [*] : logical           



The reference to the file that you want to write the dimensions to. This reference must be created by the addfile function.


An array of dimension names you want to write to thefile.


An array of dimension sizes of the dimensions you want to write to thefile.

As of version 6.0.0, this can be of type long, allowing dimension sizes greater than or equal to 2 gigabytes (GB) on 64-bit systems.


An array of logical values indicating whether the corresponding dimensions are unlimited in size.

Note that netCDF only allows one unlimited dimension, and it must be the leftmost dimension of every variable you write to the file.


The filedimdef procedure is used to pre-define dimensions in a file. The supported file must have been opened as either read/write ("w") or create ("c").

The fourth argument allows the dimension to be defined as unlimited. Currently, netCDF files only allow one dimension to be unlimited, and this dimension must be the leftmost dimension of your variable. Unlimited dimensions can grow while normal dimensions can not. A typical use of unlimited dimensions is to create a data from multiple input files. For unlimited dimensions the size value is ignored. Unlimited dimensions have a size of 0 until a variable with the unlimited dimension name is assigned to the file.

Using this procedure is much more efficient than writing a variable's dimensions one at a time. See an example of how to use this function and other functions for efficient writing of netCDF files.

See Also

fileattdef, filevarattdef, filevardef, filedimdef


Write dimensions "lon", "lat", "lev, and "time" to a netCDF file, with "time" being an unlimited dimension:

  ncf = addfile("","c")
; Define dimensions.
  nlon =  64
  nlat = 128
  nlev =  10
  ntim =  -1

  dim_names = (/ "lon",  "lat",  "lev", "time" /)
  dim_sizes = (/ nlon ,  nlat ,  nlev ,  ntim  /)
  dimUnlim = (/ False , False,  False ,  True  /)
  filedimdef( ncf, dim_names, dim_sizes, dimUnlim )
"ncdump" produces the following output:
netcdf myfile {
        lon = 64 ;
        lat = 128 ;
        lev = 10 ;
        time = UNLIMITED ; // (0 currently)