/**
\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++ or \c C 
programming language. 

\section requirementsLEMON Hardware and software requirements

Hardware requirements ...

You will also need a C++ compiler. We mostly used the Gnu C++ Compiler (g++),
from version 3.0 upwards. We also checked the Intel C compiler
(icc). Unfortunately, Visual C++ compiler knows not enough to compile the
library, so if you are using Microsoft Windows, then try to compile under
Cygwin. 

Ide kell írni:
 
-Hol fordul (Windows-os fordító nem fordítja, unix/linux alatt gcc hanyas verziója kell)
-

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 the issued distributions
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 lemon-0.3.1) and issue the following commands:

\code
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
\endcode

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

\code
tar xvzf lemon-0.3.1.tar.gz
\endcode
This command untars the <tt>tar.gz</tt> file into a directory named <tt> lemon-0.3.1</tt>.

\code
cd lemon-0.3.1
\endcode
Enters the directory.

\code
./configure
\endcode
Does some configuration (creates makefiles etc).

\code
make
\endcode
This command compiles the <tt> .cc</tt> files of the library package (the
implementation of non-template functions and classes and some test and demo
programs) and creates the very important <b> libemon.la </b> file. When
linking your program that uses LEMON it needs to access this file.

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

\code
make install
\endcode
This will copy the directory structure to its final destination (e.g. to \c
/usr/local) so that your system can access it.

\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 to have a first working program that uses library LEMON.

\code
#include <iostream>
#include <lemon/list_graph.h>

using namespace lemon;

int main()
{
  typedef ListGraph Graph;
  typedef Graph::EdgeIt EdgeIt;
  typedef Graph::NodeIt NodeIt;

  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 hemon.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):
\code
g++ hemon.cc -o hemon -lemon
\endcode

As a result you will get the exacutable \c hemon in
this directory that you can run by the command 
\code
./hemon
\endcode


If everything has gone well then the previous code fragment prints out the following:

\code
Nodes: 2 1 0

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

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! 


*/