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NetCDF User's Guide for FORTRAN
This chapter contains answers to some of the most frequently asked questions about netCDF. A more comprehensive and up-to-date FAQ document for netCDF is maintained at http://www.unidata.ucar.edu/packages/netcdf/faq.html
.
NetCDF (network Common Data Form) is an interface for array-oriented data access and a freely-distributed collection of software libraries for C, FORTRAN, C++, and Perl that provide implementations of the interface. The netCDF software was developed by Glenn Davis, Russ Rew, and Steve Emmerson at the Unidata Program Center in Boulder, Colorado, and augmented by contributions from other netCDF users. The netCDF libraries define a machine-independent format for representing arrays. Together, the interface, libraries, and format support the creation, access, and sharing of array-oriented data.
NetCDF data is:
Source distributions are available via anonymous FTP from the directory
ftp://ftp.unidata.ucar.edu/pub/netcdf/
.
Files in that directory include:
| A compressed tar file of source code for the latest general release. |
| The current beta-test release. |
Binary distributions for some platforms are available from the directory
ftp://ftp.unidata.ucar.edu/pub/binary/
Source for the Perl interface is available as a separate package, via anonymous FTP from the directory
ftp://ftp.unidata.ucar.edu/pub/netcdf-perl/
.
Yes, the latest version of this FAQ document as well as a hypertext version of the NetCDF User's Guide and other information about netCDF are available from
http://www.unidata.ucar.edu/packages/netcdf
.
Version 3 keeps the same format, but introduces new interfaces for C and FORTRAN that provide automatic type conversion and improved type safety. For more details, see:
http://www.unidata.ucar.edu/packages/netcdf/release-notes.html
.
Yes. For information about the mailing list and how to subscribe or unsubscribe, send a message to majordomo@unidata.ucar.edu
with no subject and with the following line in the body of the message:
info netcdfgroup
The netCDF mailing list has almost 500 addresses (some of which are aliases to more addresses) in fifteen countries. Several groups have adopted netCDF as a standard way to represent some forms of array-oriented data, including groups in the atmospheric sciences, hydrology, oceanography, environmental modeling, geophysics, chromatography, mass spectrometry, and neuro-imaging.
A description of some of the projects and groups that have used netCDF is available from
http://www.unidata.ucar.edu/packages/netcdf/usage.html
.
See Chapter 9 "NetCDF File Structure and Performance," page 95, for an explanation of the physical structure of netCDF data at a high enough level to make clear the performance implications of different data organizations. See Appendix B "File Format Specification," page 115, for a detailed specification of the file format.
Programs that access netCDF data should perform all access through the documented interfaces, rather than relying on the physical format of netCDF data. That way, any future changes to the format will not require changes to programs, since any such changes will be accompanied by changes in the library to support both the old and new versions of the format.
The current version of netCDF has been tested successfully on the following platforms:
Utilities available in the current netCDF distribution from Unidata are ncdump
, for converting netCDF datasets to an ASCII human-readable form, and ncgen
for converting from the ASCII human-readable form back to a binary netCDF file or a C or FORTRAN program for generating the netCDF dataset.
Several commercial and freely available analysis and data visualization packages have been adapted to access netCDF data. More information about these packages and other software that can be used to manipulate or display netCDF data is available from
http://www.unidata.ucar.edu/packages/netcdf/software.html
.
The Scientific Data Format Information FAQ, available from http://fits.cv.nrao.edu/traffic/scidataformats/faq.html
, provides a good description of other access interfaces and formats for array-oriented data, including CDF and HDF.
If you find a bug, send a description to support@unidata.ucar.edu
. This is also the address to use for questions or discussions about netCDF that are not appropriate for the entire netcdfgroup
mailing list.
A search form is available at the bottom of the netCDF home page providing a full-text search of the support questions and answers about netCDF provided by Unidata support staff.
It provides all the functionality of the C interface (except for the mapped array access of nc_put_varm_
type and nc_get_varm_
type). With the C++ interface (http://www.unidata.ucar.edu/packages/netcdf/cxxdoc_toc.html
) no IDs are needed for netCDF components, there is no need to specify types when creating attributes, and less indirection is required for dealing with dimensions. However, the C++ interface is less mature and less-widely used than the C interface, and the documentation for the C++ interface is less extensive, assuming a familiarity with the netCDF data model and the C interface.
It provides all the functionality of the C interface. The FORTRAN interface uses FORTRAN conventions for array indices, subscript order, and strings. There is no difference in the on-disk format for data written from the different language interfaces. Data written by a C language program may be read from a FORTRAN program and vice-versa.
It provides all the functionality of the C interface. The Perl interface (http://www.unidata.ucar.edu/packages/netcdf-perl/
) uses Perl conventions for arrays and strings. There is no difference in the on-disk format for data written from the different language interfaces. Data written by a C language program may be read from a Perl program and vice-versa.
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