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A Tour of NTL: Obtaining and Installing NTL for Windows and other Platforms

The WinNTL distribution of NTL can be used on any Windows 95 or NT platform (but not on Windows 3.11 or earlier). Actually, there is nothing Windows-specific about WinNTL. The source code is identical to the UNIX NTL distribution; only the packaging is slightly different, and no assumptions are made about the program development environment. Thus, it should be possible to install WinNTL on other operating systems (e.g., Macintosh, OS/2) with little difficulty.

MAC OSX Users: since MAC OSX is essentially just a (rather funny) flavor of Unix, you will be much better served using the Unix distribution.

Obtaining and unpacking NTL.

To obtain the source code and documentation for NTL, download `WinNTL-xxx.zip`. Here, "`xxx`" is the current version number. Then `unzip` this file into a directory (folder). This will unpack everything into a directory called "`WinNTL-xxx`". Inside this directory, you will find several directories.

- The directory "`doc`" contains all of NTL's documentation, including this "tour" ("`tour.html`") and the "`.txt`" files explaining each module, which can be accessed directly, or through the "tour".

- The directory "`src`" contains all of the source files for the library, all with "`.cpp`" extensions. The file "`lip.cpp`" can be compiled as a C source file (this can sometimes yield a marginal performance gain).

- The directory "`include`" contains a single directory called "`NTL`", and the latter contains all of the "`.h`" files.

Platform dependent macros.

In directory "`include/NTL`" there is a file called "`mach_desc.h`", which contains all of the platform-dependent macro definitions. The default settings should be correct for any x86- or Pentium-based system running Windows; however, the correct definitions can depend on the compiler and run-time environment. Therefore, to be on the safe side, you might consider compiling and running the program `MakeDesc`, whose source files are in directory "`MakeDesc`". This program will dynamically build a correct "`mach_desc.h`" for your platform (processor, compiler, run-time environment). To get accurate results, you must compile this program using the level of optimization (or higher) that you will use for NTL. The program will print some diagnostics to the screen, and create the file "`mach_desc.h`" (in the current directory, and not in the "`include/NTL`" directory, where it needs to go).

Configuration flags.

Also in directory "`include/NTL`" is a file called "`config.h`". You can edit this file to override some of NTL's default options for basic configuration and performance.

Basic configuration options.
  Most of the these flags are rather esoteric and can be safely ignored.

  One exception to this is the `NTL_STD_CXX` flag (or perhaps just the `NTL_PSTD_NNS` flag) which you will want to unset if your compiler is too old to handle it. Go here for details.

  Another exception are the flags to use GMP for potentially faster long integer arithmetic. See the GMP section for more details. Note that getting GMP to run on Windows is a pain in the neck. If you really want to use GMP, use Unix or Linux!

Performance options.
  These flags let you fine tune for best performance. (If you were using Unix, you could run a script that automatically selects the best settings for your platform.)

  TIP for Pentium platforms:

  - Users running on a Pentium, or other x86-like processor, will almost surely want to set the `NTL_LONG_LONG` flag, or possibly the `NTL_AVOID_FLOAT` flag, in file `config.h` to get the best performance for long integer arithmetic. If you set either of these flags, you should also set the `NTL_TBL_REM` flag as well, to get the best performance for `ZZ_pX` arithmetic. You might also want to set the `NTL_SPMM_ULL` or `NTL_SMPP_UL` flags.
  - These flags can be useful on other platforms as well, especially on processors with slow int/float conversion.
  - The best thing is to experiment, and compile and run program `QuickTest` to see the impact on the running time of various basic operations.

Note that the file "`def_config.h`" contains a backup copy of the original `config.h` file.

Test programs.

The directory "`tests`" contains several test programs. For each program `FooTest`, there is a source file "`FooTest.cpp`", and optionally two files "`FooTestIn`" and "`FooTestOut`". If the latter exist, then the program should be run with the "`FooTestIn`" as standard input; correct output (printed to standard output) should match the contents of "`FooTestOut`" exactly; note that these programs also print diagnostic output on the screen (through standard error output).

Timing functions.

The directory "`GetTime`" contains several alternative definitions of the `GetTime()` function. The file "`GetTime.cpp`" in the "`src`" directory should be OK, but your compiler might like one of the definitions in the directory "`GetTime`" better.

Other tools.

The directory "`misc`" contains a program `newnames.cpp` to help make the transition to NTL version 3.5 from earlier versions of NTL. See the changes section for more details. It also contains the programs `gen_lip_gmp_aux.cpp` and `gen_gmp_aux.cpp` that automatically generate the auxilliary files needed when using NTL with GMP. You will have to look at the makefile in the Unix distribution to see how to use these.

Compiling NTL.

Since there are a number of incompatible compilers and program development environments available for Windows, no attempt has been made to provide automatic tools for building and testing, as is done for the Unix distribution. Nevertheless, it should be straightforward to install NTL (even if it involves a bit of pointing and clicking). First, compile all of the files in "`src`", and create a static library. Make sure the compiler knows where to find NTL's include files (directory "`include`" and not "`include/NTL`") Then, to compile a program using the library, make sure the compiler knows about the library and the directory of NTL's include files. In any case, if you want to do any serious computations, you will certainly want to compile everything with your compiler's code optimizer on.

For the benefit of those who must use Microsoft Visual C++ on Windows, here are some steps for compiling and using NTL. These steps work with MSVC++ v6. While these steps seem to do the job, there may be other steps that work better. The following steps may be used to build the library, and to build and run program `QuickTest`, as a simple console application, using the library. The instructions assume you have already unzipped NTL into a directory `c:\mystuff`, and are running the MSVC++ Development Studio.

I hope these instructions make some sense: I don't know a good language for accuratly describing the particular pointing an clicking steps.

    File -> New -> Projects
       project name: ntl
       location[default]: c:\Program Files\Microsoft Visual Studio\MyProjects\ntl
       Click on Win32 static library
       Click on OK
       pre-compiled headers[default]: no
       MFC support[default]: no
       Click on Finish
       Click on OK

    Project -> Add to Project -> Files
       select all files in c:\mystuff\WinNTL-xxx\src and click on OK.

    Project -> Settings -> C/C++
       Category: Preprocessor.
       Additional include directories: c:\mystuff\WinNTL-xxx\include.
       Click on OK.

    Build -> build ntl.lib

    File -> New -> Projects -> Win32 Console Application
       project name: test
       location[default]: c:\Program Files\Microsoft Visual Studio\MyProjects\ntl
       Click on Win32 Console Application
       Click on OK
       What kind of windows application...? [default]: An empty project
       Click on Finish
       Click on OK

    Project -> Add to Project -> Files
       select the file c:\mystuff\WinNTL-xxx\tests\QuickTest.cpp
       Click on OK

    Project -> Add to Project -> Files
       select the file
          c:\Program Files\Microsoft Visual Studio\MyProjects\ntl\Debug\ntl.lib
       Note: one must select Files of type: Library Files (.lib) to make this
          file visible in the pop-up window.
       Click on OK

    Project -> Settings -> C/C++
       Category: Preprocessor.
       Additional include directories: c:\mystuff\WinNTL-xxx\include.
       Click on OK.

    Build -> build test.exe

    Build -> execute test.exe

Further remarks.

TIP: When writing programs using NTL, you should include files using the syntax

       #include <NTL/ZZ.h>

and not using a backslash ("`\`") as a delimiter.

TIP: When writing windows applications using NTL (as opposed to console applications) you might want to compile your program with the `NTL_NO_MIN_MAX` macro defined. This suppresses the declaration of several `min` and `max` functions in file `tools.h` that conflict with macro names in the MFC header files. Do not attempt to build the library with this macro defined -- only programs that use the library.

NTL has been successfully installed and tested on Windows 95 platforms with both the Microsoft and Borland compilers.

If you have installed the Unix tools from Cygnus, then you can use the Unix distribution of NTL. This distribution has been specially tailored to work smoothly with Cygnus tools. For many programmers, this is a much more comfortable and reliable program development environment than commercial systems like those from Microsoft and Borland. And moreover, these Unix tools are free. Of course, an even better approach is to install Linux on your PC.