/**

\page getstart How to start using LEMON

In this page we detail how to start using LEMON, from downloading it to

your computer, through the steps of installation, to showing a simple

"Hello World" type program that already uses LEMON. We assume that you

have a basic knowledge of your operating system and \c C++ programming

language. The procedure is pretty straightforward, but if you have any

difficulties don't hesitate to

<a href="http://lemon.cs.elte.hu/mailinglists.html">ask</a>.

\section requirementsLEMON Hardware and software requirements

In LEMON we use C++ templates heavily, thus compilation takes a

considerable amount of time and memory. So some decent box would be

advantageous. But otherwise there are no special hardware requirements.

You will need a recent C++ compiler. Our primary target is the GNU C++

Compiler (g++), from version 3.3 upwards. We also checked the Intel C

compiler (icc). Microsoft Visual C++ .NET version was also reported to

work (but not the earlier versions). If you want to develop with LEMON

under Windows you could consider using Cygwin.

In this description we will suppose a linux environment and GNU C Compiler.

\section downloadLEMON How to download LEMON

You can download LEMON from the LEMON web site:

http://lemon.cs.elte.hu/dowload.html.

There you will find released versions in form of <tt>.tar.gz</tt> files.

If you want a developer version (for example you want to contribute in

developing the library LEMON) then you might want to use our Subversion

repository. This case is not detailed here, so from now on we suppose that

you downloaded a tar.gz file.

\section installLEMON How to install LEMON

In order to install LEMON you have to do the following

Download the tarball (named <tt>lemon-x.y.z.tar.gz</tt> where \c x,\c y

and \c z are numbers indicating the version of the library: in our example

we will have <tt>lemon-0.3.1.tar.gz</tt>) and issue the following

commands:

\verbatim

tar xvzf lemon-0.3.1.tar.gz

cd lemon-0.3.1

./configure

make

make check   #(This is optional, but recomended. It runs a bunch of tests.)

make install

\endverbatim

These commands install LEMON under \c /usr/local (you will

need root privileges to be able to install to that

directory). If you want to install it to some other place, then

pass the \c --prefix=DIR flag to \c ./configure. In what follows

we will assume that you were able to install to directory

\c /usr/local, otherwise some extra care is to be taken to use the

library.

We briefly explain these commands below.

\verbatim

tar xvzf lemon-0.3.1.tar.gz

\endverbatim

This command untars the <tt>tar.gz</tt> file into a directory named <tt>

lemon-0.3.1</tt>.

\verbatim

cd lemon-0.3.1

\endverbatim

Enters the directory.

\verbatim

./configure

\endverbatim

Does some configuration (creates makefiles etc).

\todo Explain the most important switches here (gui, doc, glpk, cplex).

\verbatim

make

\endverbatim

This command compiles the non-template part of LEMON into

<b>libemon.a</b> file. It also compiles some benchmark and demo

programs.

\verbatim

make check

\endverbatim

This is an optional step: it runs the test programs that we

developed for LEMON to check whether the library works properly on

your platform.

\verbatim

make install

\endverbatim

This will copy the directory structure to its final destination (e.g. to \c

/usr/local) so that your system can access it. This command should

be issued as "root", unless you provided a \c --prefix switch to

the \c cofugure to install the library in non-default location.

\section helloworld My first program using LEMON

If you have installed LEMON on your system you can paste the

following code segment into a file (named e.g. \c hello_lemon.cc)

to have a first working program that uses library LEMON.

\code

#include <iostream>

#include <lemon/list_graph.h>

int main()

{

  typedef lemon::ListGraph Graph;

  typedef Graph::EdgeIt EdgeIt;

  typedef Graph::NodeIt NodeIt;

  using lemon::INVALID;

  Graph g;

  for (int i = 0; i < 3; i++)

    g.addNode();

  for (NodeIt i(g); i!=INVALID; ++i)

    for (NodeIt j(g); j!=INVALID; ++j)

      if (i != j) g.addEdge(i, j);

  std::cout << "Nodes:";

  for (NodeIt i(g); i!=INVALID; ++i)

    std::cout << " " << g.id(i);

  std::cout << std::endl;

  std::cout << "Edges:";

  for (EdgeIt i(g); i!=INVALID; ++i)

    std::cout << " (" << g.id(g.source(i)) << "," << g.id(g.target(i)) << ")";

  std::cout << std::endl;

}

\endcode

First let us briefly explain how this program works.

ListGraph is one of LEMON's graph classes. It is based on linked lists,

therefore iterating throuh its edges and nodes is fast.

After some convenient typedefs we create a graph and add three nodes to it.

Then we add edges to it to form a complete graph.

Then we iterate through all nodes of the graph. We use a constructor of the

node iterator to initialize it to the first node. The operator++ is used to

step to the next node. Using operator++ on the iterator pointing to the last

node invalidates the iterator i.e. sets its value to

\ref lemon::INVALID "INVALID". This is what we exploit in the stop condition.

We can also iterate through all edges of the graph very similarly. The 

\c target and

\c source member functions can be used to access the endpoints of an edge.

If you have saved the preceding code into a file named, say, \c

hello_lemon.cc and your installation of LEMON into directory \c

/usr/local was successful then it is very easy to compile this

program with the following command (the argument <tt>-lemon</tt>

tells the compiler that we are using the installed library LEMON):

\verbatim

g++ hello_lemon.cc -o hello_lemon -lemon

\endverbatim

As a result you will get the exacutable \c hello_lemon in

this directory that you can run by the command 

\verbatim

./hello_lemon

\endverbatim

If everything has gone well then the previous code fragment prints

out the following:

\verbatim

Nodes: 2 1 0

Edges: (0,2) (1,2) (0,1) (2,1) (1,0) (2,0)

\endverbatim

Congratulations!

If you want to see more features, go to the

\ref quicktour "Quick Tour to LEMON",

if you want to see see some demo programs then go to our 

\ref demoprograms "Demo Programs" page! 

*/