-------------------------------------------------------------------------------
INTRODUCTION
-------------------------------------------------------------------------------

YAFU is the result of an ongoing hobby project to understand how to factor 
large integers, and how to factor them fast.  Various motivations exist for 
doing this, but mostly it boils down to the facts that A) I like to do it, and
B) for some reason factoring integers is cool.  The fact that integer 
factorization is used real world public-key encryption schemes, and lots of 
people owning black helicopters therefore have a vested interest in it, might 
have something to do with that.  This is not to say that YAFU is useful for
factoring public keys, but there are plenty of other numbers out there and
it is still fun to do.  A community of factorization enthusiasts can be 
found at mersenneforum.org.

-------------------------------------------------------------------------------
OVERVIEW
-------------------------------------------------------------------------------

YAFU (with assistance from other free software) uses the most powerful modern
algorithms (and implementations of them) to factor input integers in a 
completely automated way.  The automation within YAFU is state-of-the-art, 
combining factorization algorithms in an intelligent and adaptive methodology 
that minimizes the time to find the factors of arbitrary input integers.  
It is most optimized for general inputs up to 160 digits in size, although 
there is support for inputs much larger than that, if they have a special 
form.  There are also specialized functions for handling  lists of inputs and 
ranges of contiguous smaller inputs.

YAFU is primarily a command-line driven tool.  You provide the number to factor
and, via screen output and log files, YAFU will provide you the factors.  
But that's not all!  You also get an interactive environment similar to MATLAB
or PARI/GP, where you can type commands and store results.  The functionality
of this interface is limited, but perhaps useful, and I have plans to make it
better.  YAFU also provides a vast amount of flexibility, through many many
options and a very capable expression interpreter.  If you know what you are
doing, or if you read the documentation enough, you can customize the operation
of YAFU a great deal.  You should have received a copy of docfile.txt, which
explains in some detail all of the available functions, how to use them,
and how to influence their behavior.

-------------------------------------------------------------------------------
INSTALLATION
-------------------------------------------------------------------------------

No installation necessary, just put the binary in whatever location you like 
and run it.  Files that YAFU generates are placed alonside the binary, and 
directories/files that YAFU needs are with respect to the binary location 
(such as the ggnfs sievers, see below)

Support and an active user community can be found here:
http://www.mersenneforum.org/forumdisplay.php?f=96

-------------------------------------------------------------------------------
INSTALLATION WITH NUMBER FIELD SIEVE (NFS) SUPPORT
-------------------------------------------------------------------------------

To run the general or special number field sieve using YAFU, you will need to 
provide ggnfs executable files and make the location of these files known to 
YAFU at runtime.  The easiest way to obtain the files is through Jeff 
Gilchrist's website: http://gilchrist.ca/jeff/factoring/index.html

Download the .zip file for your OS and unzip it to a directory  on your 
computer.  The easiest way to let yafu know where these are is to create/modify  
a yafu.ini file (which should appear in the same directory as your YAFU 
executable) to contain a line specifying ggnfs_dir in the following way:
ggnfs_dir=<location relative to yafu executable>

For instance, if your ggnfs executables were located adjacent to
the yafu folder in the directory tree, in a folder called ggnfs-bin, then the 
line would be:
ggnfs_dir=..\ggnfs-bin\

The ggnfs executables accomplish the sieving portion of NFS.  The other phases
are all handled internally to YAFU via a supporting library, msieve.  Here are
some quick references on for more information about the number field sieve 
or msieve:
http://mathworld.wolfram.com/NumberFieldSieve.html
http://en.wikipedia.org/wiki/General_number_field_sieve
http://sourceforge.net/projects/msieve/
http://www.boo.net/~jasonp/qs.html

-------------------------------------------------------------------------------
BUILD INFORMATION
-------------------------------------------------------------------------------

Pre-compiled binaries are provided for windows.  However, anyone 
is welcome to compile from source for your own system.  If you can make a 
binary which beats the performance of one of the pre-compiled versions for a 
particular architecture, I'd love to hear about it!

Linux 64 bit OS (including Windows Subsystem for Linux, WSL)
=============
make yafu [NFS=1] [USE_SSE41=1] [USE_AVX2=1] [USE_BMI2=1] [SKYLAKEX=1] [ICELAKE=1]

I've built and tested with gcc and icc.  Enable either by using
COMPILER=gcc or COMPILER=icc on the make line.

Optionally enable GNFS factorizations by setting NFS=1 during make.  This will 
require the makefile to be edited to point to the libmsieve.a library.  By 
default, it is assumed to be located at ../msieve/ relative to the Makefile.  

YAFU now requires several other projects to be built before yafu.  These are:
gmp (https://gmplib.org/)
gmp-ecm (http://ecm.gforge.inria.fr/)
ytools (https://github.com/bbuhrow/ytools)
ysieve (https://github.com/bbuhrow/ysieve)

Some support can be had here:
http://www.mersenneforum.org/forumdisplay.php?f=96

If your computer supports them, yafu can make use of several modern instruction
set extensions, including SSE41, AVX2, and AVX512 (various extensions).
SKYLAKEX will add support for AVX512F and AVX512BW.
ICELAKE will add support for AVX512F, AVX512BW, and AVX512IFMA.
Primarily these are used in SIQS.  If you have AVX512 on your cpu, yafu will
also use AVX-ECM as the default ECM implementation.  For a standalone 
version of AVX-ECM, please refer to:
https://github.com/bbuhrow/avx-ecm




WINDOWS MS Visual Studio
=============

Build files are available for several versions of MSVC.  The directory structure is 
important for these builds, especially if GMP-ECM or NFS support is desired.  
The build files expect to see an mpir, msieve, gmp-ecm, ytools, and ysieve folder at 
the same  level as the YAFU folder in the directory tree, with the following structure:

msieve
	build.vc10
		common
			Win32
				Release					
					common.lib
			x64
				Release					
					common.lib
		gnfs
			Win32
				Release
					gnfs.lib
			x64
				Release
					gnfs.lib

gmp-ecm
	ecm.h
	config.h
	build.vc9
		Win32
			Release
				ecm.lib
		x64
			Release
				ecm.lib
	build.vc10
		Win32
			Release
				libecm.lib
		x64
			Release
				libecm.lib
mpir
	gmp.h
	config.h
	gmp-mparam.h
	mpir.h
	build.vc9
		Win32
			Release
				mpir.lib
		x64
			Release
				mpir.lib
	build.vc10
		Win32
			Release
				mpir.lib
		x64
			Release
				mpir.lib
				
yafu
    trunk
        build.vc9
            ...
        build.vc10
            ...
            
ytools
    ytools
        x64
            Release
                ytools.lib
ysieve
    ysieve_lib
        x64
            Release
                ysieve_lib.lib
                    
		
The mpir and gmp-ecm libraries will need to be built separately, for either 
Win32 or x64 targets.  To change the target for a yafu build, within MSVC 
select Build -> Configuration Manger then in the Active Solution Platform 
pulldown choose x64 or Win32.

MINGW-64
=============
YAFU should build in mingw-64 environment.  The  src zip file should 
include a Makefile.mingw for this purpose.  The build should be similar to
a linux build.  This option is less-well tested.

OTHER
=============
If you build yafu on other platforms or using other IDE's or
compilers, please let me know about it.


-------------------------------------------------------------------------------
HELP INFORMATION
-------------------------------------------------------------------------------

Detailed documentation is available in docfile.txt, which can be viewed during 
an interactive YAFU session by typing 'help'.  The default yafu.ini also 
contains descriptions of available options.

If you want to see the docfile from within the program, it needs to be in the 
same directory as the executable.

Check back at https://github.com/bbuhrow/yafu for updates.

---------------------------------------------------------------
MISC INFORMATION
---------------------------------------------------------------
Here's a fun test case for factor(), which uses many of the 
algorithms in yafu
factor(2056802480868100646375721251575555494408897387375737955882170045672576386016591560879707933101909539325829251496440620798637813)

neat example for ecm:
140870298550359924914704160737419905257747544866892632000062896476968602578482966342704