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CFD General Notation System


CGNS site pages
What is CGNS?
Getting Started
Latest News
Switch to HDF5
Steering Committee
Discussion Group
Contributed Utilities
Example CGNS Files
Proposed Extensions

Documentation pages
Documentation Home
Papers and Slides
Meeting Minutes
User's Guide
SIDS File Mapping
Mid-Level Library
CGIO User's Guide

SourceForge pages
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If you have not done so already, please REGISTER by e-mailing to the CGNS REGISTRAR the following information:
  • Your name
  • Company, university, lab, or facility name (if applicable)
  • Email, if different from your current sending address
  • Intended use for CGNS
Although there is no registration requirement in order to obtain CGNS, by registering you will help the CGNS team to serve its users better.

We also strongly recommend that you join the Discussion Group. This forum is the primary method used to keep CGNS users current with release and other important information updates. It is also used for discussing important problems/issues and for obtaining help from other CGNS users.

What to Download

As a minimum, you will need to download and compile the CGNS library code. Compilation requires an ANSI compliant C compiler. The source code may downloaded (from SourceForge) as a gzipped, tar file:
  • Current Stable Release: CGNS Version 3.2.1 (cgnslib_3.2.1.tar.gz)
    This Version 3.2 release provides full integration of parallel I/O using HDF5 with MPI. It also implements the Hierarchy of families (CPEX 0033), Multiple families (CPEX 0034), and Cubic elements (CPEX 0036). Compression (rewriting) of modified CGNS files is no longer automatically done, since this may interfere with parallel I/O. This may be reenabled within an application with the cg_set_compress function, or done later through the CGNSview GUI or with the cgnscompress program in the tools subdirectory. Conversion programs to and from AFLR3, FAST, and TetGen have also been added to CGNStools.

    Release 3.2.1 implements the suggestions by Cambridge Flow Solutions to the CMake scripts and adds routines to set the MPI communicator for parallel I/O. There are also numerous updates and fixes to the test cases, tools and CGNStools utilities.

    Note: CGNStools is no longer built automatically, you need to set the configure flag, --enable-cgnstools if using configure.

  • Previous Stable Releases:
    CGNS Version 3.1.4, Release 2 (cgnslib_3.1.4-2.tar.gz)
    Second release of Version 3.1.4 software. Includes 64-bit integer capability and updated Tools for viewing and editing CGNS files. HDF5 is now the default file type, when CGNS is built with HDF5 version 1.8 or later. (CGNS can always read or write both HDF5 and ADF file types.)

  • CGNS Version 2.5-5 (cgnslib_2.5-5.tar.gz)
    Prior Version 2.x stable-release version. (This release fixes a long standing issue of memory leakage in the CGNS library when closing a file or deleting a node. It also removes the internal storage of element data when reading and writing, and uses the user supplied buffer instead. In the case of partial reads and writes however, the element data is currently reloaded into memory to do the operations.)

Also available from the SourceForge CGNS Files Download page:

Other CGNS related software and older versions of the library are also available. (NOTE: if building CGNS with an HDF5 version earlier than 1.8, then links will not work when using HDF5 file type.)

Note about Compilers

Users should be aware that many new features in CGNS require the use of up-to-date compilers. For example, older FORTRAN compilers that are not FORTRAN 2003 compliant (such as g77) will not work for many CGNS features, and are not recommended or supported.

Note to Users of Version 2.5 CGNS

Current users of Version 2.5 should read the following short guide:

which describes some of the reasons for upgrading to the latest version 3 software as well as how to handle portability issues between versions.

Known Bugs/Issues in Latest Official Release

  • In the file /cgns/trunk/src/, the comment lines on the first 28 lines should be changed from "c" to "!". This has been fixed in the SVN version of the code.
  • In the file /cgns/trunk/src/cgnslib.h, the macro I could conflict with the I in complex.h (if used). This has been fixed in the SVN version of the code by redefining I to Ii.
  • Parallel cgp_open can show major slowdown when many processors are employed. This issue is being worked.