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Re: Read cdf files using fortran

It is usually easy to read cdf files using fortran. A simple
subroutine which does that is pasted below, with comments. A
useful tool is the unix command ncdump -h filename.cdf, which 
shows you the header information in the netcdf file. In the
example subroutine below, ncdump will give you the grid sizes

The procedure is: 1) open the netcdf file; 2) read the variable
number in the cdf file from the header; 3) read the data; 
4) close the file.

It is pretty straightforward for simple files. For more 
complicated files, there is a lot of documentation in the 
Ferret manual.

Billy K

        subroutine cdf_read (fname,vname,nx,ny,nt,data)

        include '/opt/local/include/netcdf.inc'	  ! system-specific

        real data(nx,ny,nt)		! data grid to read

        character *31 fname		! filename to read from
        character *9 vname		! variable name to read

        integer lower(3),upper(3)	! 3-dimensional array

        integer dnum		! DNUM is the variable order number
	integer ir		! IR is a flag for netcdf library calls
c....................IR is returned by each call to the netcdf library. 
c....................IR will be 0 for a successful call, 1 otherwise. 
c....................I'm not using IR here, else set flags to test it.

        data lower/1,1,1/	! lower contains the lower corner indices

        upper(1)=nx		! upper contains the upper corner indices

c.......................open the netcdf file for reading only (NCNOWRIT)

        dnum=ncvid(ncid,vname,ir)	! get the variable number DNUM
        call ncvgt(ncid,dnum,lower,upper,data,ir)    ! read the data

        call ncclos(ncid,ir)		! close the file


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