|The Finite Element ToolKit|
Developed by the MCP Research Group
at the UCSD Center for Computational Mathematics
PUNC User's Guide
Table of Contents
PUNC (Portable Understructure for Numerical Computing) is a small standard collection of software libraries for numerical computing. The PUNC collection includes reference implementations of the standard (dense matrix) linear algebra tools BLAS and LAPACK, and also includes some newer (sparse matrix) linear algebra tools ARPACK, SuperLU, CgCode, and PMG. PUNC also provides some additional basic infrastructure such as the standard F2C header and corresponding library (libF2C), to support the use of F2C'd FORTRAN codes, and some other standard tools used to build numerical simulation software, such as the HDF5 library. While most of the libraries included in PUNC are completely stand-alone, and are the reference implementations developed by the individual library authors, PUNC also provides some Object-oriented C wrappers (written by the FETK developers) for use with Object-oriented C/C++ codes such as FETK . This is accomplished by building PUNC on top of FETK 's MALOC library.
PUNC installs it self minimally, in that if it can find a vendor-supplied version of one of its libraries, it does not build that particular library (unless the installer overrides the configuration and forces PUNC to build a particular library that already exists on the platform). At the end of the PUNC installation, you have a reference collection of the standard numerical software libraries listed above, formed from a combination of any vendor or hand-tuned libraries it found on your platform, together with any additional libraries that were built by PUNC during installation.
PUNC is a class library written in Clean OO C. "Clean" refers to the fact that the language is both legal C++ and legal ANSI/ISO/Standard C, and can be compiled with any standard C or C++ compiler. "OO" refers to the programming style employed -- object-oriented. An Clean OO C implementation consists of a set of "Objects" (Clean C structs) which are operated on by a collection of "methods" (Clean C subroutines) which always have a pointer to the Object as their first argument. This special argument is always written as "thee", analogous to the implicit "this" pointer in C++. (An Clean OO C implementation can be turned into a C++ implementation with a simple AWK/SED or Perl Script.) As a result of this Clean OO C implementation, PUNC can be used as a set of C++-like class libraries, it can be safely software engineered into other large software packages, and it can be built on just about any UNIX-like platform with either a C or a C++ compiler, including e.g. Linux, IRIX, and Win32. To use some of the graphics and parallel computing features, your platform must also have some form of standard INET sockets (WINSOCK will work). PUNC is easily buildable from source on any UNIX-like system, and uses a GNU autoconf build environment.
Information and Resources
Detailed information about PUNC can be found in the User's Guide and Programmers's Guide.
While PUNC is itself a self-contained software package, it is one of several components of FETK (the Finite Element ToolKit). FETK consists of the following components written in Clean OO C:
MALOC is self-contained, and requires only an ANSI-C compiler on a UNIX or Win32 platform. PUNC, GAMer, SG, and MC are also self-contained, but rely on MALOC having been previously installed on the platform. Additional features of MC are enabled if PUNC is available, but PUNC is not required to build MC. The MC eXtension libraries MCX are constructed on top of MALOC and MC, and in order install and use MCX one must first correctly configure and install both MALOC and MC. MCX is made up of a number of individual libraries developed by members of our group, or contributed by one of a number of colleagues. More information about FETK can be found on the FETK website:
PUNC is copyrighted, but is redistributable in source and binary form under the following license. The PUNC source can be downloaded from the FETK Download Page.
PUNC uses the low-level FETK abstraction library MALOC, which must be installed before installing PUNC.
Frequently Asked Questions
What is PUNC and what does PUNC stand for?
See the Overview.
How to I obtain a copy of the PUNC binaries and/or source code?
See the Obtaining PUNC section.
I managed to get a copy of "punc-VERSION.[i386|src|tar].[rpm|gz]"; how do I now install PUNC?
See the Installation Instructions.
You gave me a "patch.gz" file to fix a bug in PUNC; how do I apply the patch?
To apply patches to upgrade PUNC to a new version, you first obtain the patch from me or my webpage as a single file with a name like "patch.gz". You apply the patch after you have unpacked the punc-VERSION.tar.gz file as described in the installation instructions. To apply the patch, cd into the directory containing the root PUNC directory (called "punc" after unpacking punc-VERSION.tar.gz) and execute the "patch" program as follows (the patch program exists on most UNIX machines):
Patch files are simply the output from a recursive "diff" that are used to represent all differences between two directory trees. For example, to create a patch representing the changes from version 1.0 of PUNC (in directory punc_1.0 for example) to version 1.1 of PUNC (e.g. in directory punc_1.1), I would normally type the following:
I really don't know what I'm doing; how to I get more documentation for PUNC?
The User's Guide and the Programmers's Guide contain all of the PUNC documentation.
Why did you develop PUNC? Can't you just use BLAS and possibly LAPACK?
Yes, we definitely need to use LAPACK (built on the BLAS). However, modern PDE simulation codes involve applying, inverting, or analyzing the spectral properties of very large sparse matrices, so modern sparse matrix libraries that have much of the capabilities of LAPACK must be used. LAPACK was an update to LINPACK (direct methods and factorizations for dense and banded matrices) and EISPACK (methods for computing the eigenpairs of dense and banded matrices). SuperLU and ARPACK can be viewed as providing these same general capabilities (respectively) but for sparse matrices. CgCode and PMG (two choices out of a number that could have been made) provide additional capabilities not in any of the other libraries, namely the iterative solution of large sparse linear systems using CG-type methods and Multilevel methods.
One often needs to use many or most of these tools for the development of numerical PDE simulation software, but it is often quite complex to install all of these packages and to be certain that they are working as designed on the particular platform. PUNC basically provides three things: (1) reference implementations of these libraries to flesh out your computing platform; (2) convenient portable configuration and installation of some or all of the libraries; and (3) additional basic infrastructure for using these libraries together and with other software.
What is in all of these subdirectories? Where exactly is "PUNC"?
PUNC consists of several (class) libraries from which you will call routines to handle your application. You simply link your application to the PUNC static or shared library. The MC package automatically looks for the PUNC libraries as part of its Autoconf configuration process.
punc | ------------------------ / | | | \ config doc examples src tools
The src directory has the additional subdirectory structure:
src | ----------------------------------------------------- / | | | | | | | | \ aaa_inc aaa_lib base blas lapack arpack superlu cgcode pmg vf2c
Within each library source directory is an additional subdirectory, "punc". The "punc" subdirectory contains public headers for the library, representing the library API; these headers will be installed in the specified header install directory during the install procedure after building PUNC.
The following is a brief description of each subdirectory of the package.
punc - The entire PUNC package punc/config - GNU Autoconf scripts and non-unix config files punc/doc - PUNC documentation punc/examples - Complex examples and data files for using PUNC punc/src - PUNC source code (all source and headers) punc/src/aaa_inc - Header installation tools punc/src/aaa_lib - Library installation tools punc/src/*/punc - The PUNC headers (API) punc/src/base - Source for M. Holst's BASE (PUNC foundation headers) punc/src/pmg - Source for M. Holst's PMG (Parallel MultiGrid) punc/src/blas - Source for Reference Implementation of BLAS punc/src/lapack - Source for Reference Implementation of LAPACK punc/src/arpack - Source for Reference Implementation of ARPACK punc/src/superlu - Source for Reference Implementation of SuperLU punc/src/cgcode - Source for Reference Implementation of CgCode punc/src/vf2c - Source for Reference Implementation of F2C punc/tools - Some binary tools for use with PUNC
Okay, I seem to have installed PUNC correctly; how do I actually use it now?
Using PUNC is pretty simple; it is a very object-oriented implementation, although it is written in C. It is actually written in an object-oriented way using a subset of ANSI/Standard C, sometimes referred to as Clean OO C. Clean C refers to the overlapping subset of ANSI/Standard C and C++, so you can compile the code as a legal C++ or ANSI/Standard C code. Using the code consists of constructing objects (represented by C structs) and manipulating these objects using appropriate methods (represented by C functions which follow a certain object-oriented prototype convention).
What is the class hierarchy? How are the various libraries related?
Detailed information on the class relationships can be found in the Programmers's Guide. The following directed graph shows the class library dependencies. (This tends to evolve as PUNC is developed.)
ANSI-C ======> base ======> vf2c ======> superlu F2C+ANSI-C ==> blas ==> lapack ==> arpack ==> cgcode ==> pmg
Wait! I have a bunch of other questions, such as:
Available distribution formats
PUNC is distributed in both binary format (as a binary RPM file punc-VERSION.i386.rpm for i386-based versions of Linux) and in source format (as a source RPM file punc-VERSION.src.rpm and as a gzipped tar file "punc-VERSION.tar.gz").
Installation using the binary RPM file
The following rpm command will install all of the PUNC headers and libraries into /usr/local/include and /usr/local/lib, and will install the PUNC documentation into /usr/share/doc/packages/punc:
rpm -Uvh punc-VERSION.i386.rpm
Installation and rebuilding from sources using the source RPM file
The following rpm command will unpack the source rpm file "punc-VERSON.src.rpm" into the PUNC gzipped tar file containing the sources called "punc-VERSION.tar.tar.gz" and into a small RPM spec file called "punc-VERSON.spec":
rpm -Uvh punc-VERSION.src.rpmThe sources can then be unpacked and built using the directions for the gzipped tar file below. Alternatively, the following rpm command will do these steps for you:
rpm -bp punc-VERSION.spec
Rebuilding binary and source RPM files from the gzipped tar file
The PUNC sources contain the RPM spec file "punc-VERSON.spec" in the root source directory; as a result, rebuilding the RPM files from sources can be done using the rpm command:
rpm -ta punc-VERSION.tar.gzThe result will be the corresponding source and binary rpm files, named "punc-VERSON.src.rpm" and "punc-VERSION.i386.rpm". Normally, these files are written to /usr/src/redhat/SRPMS and /usr/src/redhat/RPMS respectively, but you must be logged in as root for these to work. The destination directories can be overriden using arguments to the rpm program (see the rpm manpage).
Installation and building from sources using the gzipped tar file
The following command will unpack PUNC into a number of subdirectories and files on any UNIX machine (and on any WinNT machine with the GNU-Win32 tools gzip and tar).
gzip -dc punc-VERSION.tar.gz | tar xvf -
PUNC is essentially a portable low-level numerical software library which was assembled to support the development of MC (Manifold Code), a multilevel adaptive finite element "kernel". MC is designed to be easily extended through the use of extension packages which are constructed on top of MC, which itself is written on top of PUNC and MALOC. The installation instructions PUNC, MC, and related software are identical to the instructions below for PUNC.
Building the package using the GNU "configure" shell script and "make"
The "configure" shell script in the "punc" directory (the toplevel directory created when you unpacked the PUNC tar.gz file) will build the entire package. This is a standard GNU autoconf-generated configuration script. For a list of the possible configuration options, type:
You should be able to build PUNC by simply typing:
./configure make make install
However, it is often advantageous to keep the original source directory pristine; the configure script can actually be run outside the source tree, which will keep all files created by the build outside the source tree. (This idea is related to the section below describing how to build binaries for multiple architectures at the same time using the same source tree, and requires that your version of make has the VPATH facility, such as GNU make.) For example, I build PUNC in a separate directory from the source tree as follows:
gzip -dc punc-VERSION.tar.gz | tar xvf - mkdir punc_build cd punc_build ../punc/configure make make install
Building binaries for multiple architectures in the same source directory
If you have a version of "make" that supports the VPATH facility (such as any recent version of GNU make), then you can build the package for multiple architectures in the same source directory (in fact, you can do the compiles at the same time without collisions). This is very useful if you have your home directory on an NFS volume that you share among multiple architectures, such as SGI, Linux, etc. To build PUNC for all the systems at the same time, you simply make an additional subdirectory in the main PUNC directory for each architecture, copy "configure" into it, "cd" into the subdirectory, and then install as above. For example, on a linux machine you would do the following:
mkdir linux cp configure linux/. cd linux ./configure make make installIf you mount the same NFS home directory on for example an OpenStep box, you could at the same time do the following:
mkdir next cp configure next/. cd next ./configure make make installAgain, both builds can actually be done outside the source tree rather than in a subdirectory of the source tree, as described in the previous section.
Building shared libraries rather than static libraries
(MIKE: give an overview of libtool.)
Rebuilding the configure script and the Makefile.in files
If for some reason you actually need to rebuild the configure script or the Makefile.in files using the GNU autoconf suite, you should read the block of documentation at the top of the configure.in file. The commentary I put there explains exactly how the GNU autoconf suite must be used and in what order, and exactly what files are produced at each step of the process. A script called "bootstrap" which automates this process is located in the config subdirectory of the PUNC source tree.
Below is some platform-specific build/usage information for PUNC.
What you end up with
Once the build completes via the "configure;make;make install" procedure above with no errors, the PUNC library (libpunc.a and/or libpunc.so) is installed into the specified installation directory. You can also build some useful tools that employ the PUNC library by cd-ing into the "tools" subdirectory and repeating the "configure;make;make install" procedure.
Using PUNC on a parallel computer
PUNC provides abstractions to both INET sockets and MPI for communication support in parallel computing software; this is done through the use of the underlying MALOC library. See the MALOC documentation for more details.
Getting PUNC to find your installation of MPI
If your installation of MPI is located in an unusual directory, then the configuration script may have trouble finding the MPI library (libmpi.a) or the MPI header file (mpi.h). Again, the configure script prints out the state of affairs quite clearly as to whether it found the library and the header. If you have MPI and configure is not finding it, then here are several possible solutions, each of which usually works. They are listed in preferred order (i.e. you should try Solution 1 first, and if that doesn't work try Solution 2, and so on).
PUNC (Portable Understructure for Numerical Computing) was conceived, designed, and implemented over several years by Michael Holst, beginning with an initial implementation in 1994. Various colleagues have contributed ideas and/or code to PUNC (see the credits list below).
PUNC (Portable Understructure for Numerical Computing) Copyright (C) 1994-2010 Michael Holst TELE: (858) 534-4899 Department of Mathematics FAX: (858) 534-5273 UC San Diego, AP&M 5739 EMAIL: firstname.lastname@example.org La Jolla, CA 92093 USA WEB: http://ccom.ucsd.edu/~mholstPUNC was designed to be a portable collection of standard numerical libraries for use in the development of MC (Manifold Code), an adaptive multilevel finite element package also developed by Michael Holst. PUNC was developed almost entirely on a home-grown 90Mhz Pentium PC running various flavors of Linux and [Free|Net|Open]BSD, using primarily GNU, BSD, and other free software development tools. Most of the development occurred during the hours of 10pm to 2am on a daily basis for several years, under heavy influence of Starbuck's coffee, with helpful advice provided by Mac and Mochi (two cats knowledgable in socket programming and numerical analysis).
PUNC was released under the GNU GPL (GNU General Public License) beginning with the initial implementation in 1994, and continues to be released under this license. What this means is that like all GNU softare, PUNC is freely redistributable in source code form following the rules outlined in the text of the GNU GPL. You should have received a copy of the GNU GPL with this distribution of PUNC; a copy can be found here. If you did not receive a copy of the GNU GPL, please write to me and also write to: The Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Below is a credits list for the people that have contributed to PUNC in one way or another. The fields below follow the credits file format used in the Linux kernel CREDITS file to allow for easy manipulation via shell scripts. The fields are as follows:
N: name of contributor E: email address W: web address P: PGP key ID and fingerprint D: description of primary contributions S: snail-mail address
N: Michael Holst E: email@example.com W: http://ccom.ucsd.edu/~mholst P: 1024/0xB5212DCD D: punc/* -- The package structure D: punc/acconfig.h -- The platform abstraction information D: punc/configure.in -- The GNU autoconf/automake structure D: punc/config/* -- The GNU autoconf/automake shell scripts D: punc/doc/* -- The package documentation D: punc/examples/* -- The package examples D: punc/src/aaa_inc/* -- Library header build structure D: punc/src/aaa_lib/* -- Static and shared library build structure D: punc/src/base/* -- M. Holst's PUNC Foundation headers D: punc/src/pmg/* -- M. Holst's PMG D: punc/src/blas/* -- Reference implementation of BLAS D: punc/src/lapack/* -- Reference implementation of LAPACK D: punc/src/arpack/* -- Reference implementation of ARPACK D: punc/src/superlu/* -- Reference implementation of SuperLU D: punc/src/cgcode/* -- Reference implementation of CgCode D: punc/src/vf2c/* -- Reference implementation of F2C D: punc/tools/* -- Tools built on the libraries S: Department of Mathematics S: UC San Diego, AP&M 5739 S: La Jolla, CA 92093 USA N: Steve Bond E: firstname.lastname@example.org D: punc/punc.spec -- RPM support (for building src/binary RPMs) S: Department of Mathematics S: UC San Diego S: La Jolla, CA 92093 USA
Contacting the Author
If you have questions or comments about PUNC, please feel free to contact me at email@example.com.
This version of PUNC is distributed under the following guidelines:
The GPL (GNU General Public License) below is copyrighted by the Free Software Foundation. However, the instance of software that it refers to, my package in this case, is copyrighted by myself as the author of the package. Any additional software that I distribute with my software is copyrighted by the authors of those pieces of software (see the individual source files for author information). ---Michael Holst
GNU GENERAL PUBLIC LICENSE Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. (one line to give the program's name and a brief idea of what it does.) Copyright (C) 19yy < name of author > This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19yy name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. < signature of Ty Coon >, 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.