/*! \page whatis What is JFM?
 * 
 * JFM is a toolkit for building Linear Programming models for farm economics.  It
 * provides re-usable components for building models of any type but also provides 
 * an initial set of specific classes to implement the constraints and objective functions 
 * that form the Silsoe whole farm model.  
 * 
 * \section reltoswfm Relationship to the Silsoe Whole Farm Model 
 * 
 * The Silsoe whole farm model was originally developed by Eric Audsley 
 * and collaborators at Silsoe research institute and continues to be developed 
 * and enhanced by the team at Cranfield University. JFM is not a replacement 
 * for the Silsoe whole farm model as it lacks key features such as a user 
 * interface,  however, it is designed to facilitate larger simulations with multiple model runs, and 
 * to permit great flexibility in manipulating the underlying model specification (both at runtime and
 * in terms of ease of programming via its API). 
 * Current development of JFM and the Silsoe whole farm model is proceeding in 
 * parallel with new model features being implemented in both code-bases. JFM is based on 
 * the same linear programming model of farming systems used in the Silsoe whole farm 
 * model and described in detail in the following reference;

 Rounsevell, Annetts, Audsley, Mayr, and Reginster M. D. Rounsevell, 
 J. E. Annetts, E. Audsley, T. Mayr, and I. Reginster, <em> Agriculture, Ecosystems 
 and Environment </em> \b 95, 465 (2003). 

\section appr How JFM Solves the Linear Programme

Since JFM is a linear programme it requires a linear program solver. The only solver with which 
it has been used so far is the GNU Linear Programming Kit [http://en.wikipedia.org/wiki/GNU_Linear_Programming_Kit]. It 
should be noted however that the code connecting JFM with its solver is simple and should 
permit other solvers to be accomodated easily.

Prior to packaging the model up for solution by the LP solver, 
JFM uses an internal representation of the problem matrix. 
This internal representation is designed to minimize errors and allow the model 
framework to be extended with minimum effort. 

\section Availability

JFM Source code can be downloaded at http://code.google.com/p/javawfm/

\section Features

  * - <b> MIP. </b> Use of the MIP (Mixed Integer Programming) solver feature of the 
  * Gnu Linear Programming Kit allows model variables to be specified as integer
  *  or continous. This is particularly useful for labour and machinery where the
  *   distinction between casual (continuous variable) labour and full time labour 
  *   (integer) is sometimes important.

  * - <b> Multiple Objectives. </b> Any number of arbitrary objective functions with different 
  * weights may be applied. JFM uses a simple system whereby each model object 
  * can be assigned to particular objectives via a function call. Different objectives 
  * and weights can be declared in the xml input file

  * - \b Extensibility.  As much as possible, the process of reading inputs, using 
  * inputs to create a linear programme and packaging that programme for a solver 
  * has been divided into independent and discrete objects. As a consequence, the 
  * process of adding new constraints and new terms in the objective function is 
  * extremely easy. The internal representation of the LP model used by JFM makes 
  * it almost impossible to erroneously assign a row or column value in the problem 
  * matrix so programmers can spend their time worrying about other stuff :). 

  * - <b> Platform Independence.</b> JFM will run at full native speed on pretty much any 
  * type of computer (Windows, Mac, Linux). In order to communicate with the 
  * GNU Linear Programming Kit, a native library is needed which is platform specific.  
  * Once this platform specific library has been installed, any changes or updates to 
  * the java part of the program can be used without recompiling. 

\section Limitations
  * - <b> Arable Only.</b> At present JFM only implements parts of the original Silsoe 
  * Whole Farm Model which refer to arable systems. Livestock and grassland are not included.  

  * - <b> No GUI.</b> JFM is a set of classes rather than a pre-packaged application. 
  * It is therefore highly extensible and useful for academic research but lacks
  *  a graphical user interface that would make it useful to a more general user base. Implementation 
  *  of a GUI on top of the JFM engine would be relatively easy since the JFM uses xml as its 
  *  default input format.  

  * - <b> Soils and Rainfall  </b> The original Silsoe Whole farm model contains 
  * algorithms to calculate the number of workable hours in a given period 
  * based on rainfall and soiltype. These algorithms are not yet implemented in the JFM. 

\section roadmap Road Map
  * - <b> Social Objectives. </b> Objective functions for a variety of factors in the 
  * farmer's decision making are to be taken into account. Designing these 
  * social objectives is part of an ongoing research program 
  * [http://www.relu.ac.uk/research/projects/SecondCall/Sutherland.htm]
 * 
 * - <b> Validated Input. </b> One of the most user unfriendly aspects of JFM is its xml interface. 
 * Since xml files must presently be written by hand by users it would be useful to create a DTD to 
 * validate the xml input and provide feedback to the user on mistakes in their input files.
*/