CIsingPerfect (Version 4.02)

System requirements:
 - MacOS 7 or higher
 - PPC-Processor
 - sufficient harddisk space during the run (depending on the choice of parameters)
 - at least 4MB of free memory (12 recommended)

Installation:
 - Unstuff the file "CIsingPerfect.sit" with StuffitExpander� 

Tips:
 - Make sure that the volume which you start the program from is not write-protected
	  and has enough free space (depending on the choice of parameters, typically 
          not more than 100 MB, but in worst case up to 750 MB)
 - If you have no fast processor and you choose a supercritical activity and a large
 	  window with free or periodic boundary condition, the program may run for 
          several hours. You can interrupt the program by pressing ESC - the program then
          stops as soon as t=0.

License:
 - This software is Freeware, but comes with no guarantee.
 - You are not allowed to modify anything on the application or to disassemble it.
 - Any scientific use of this program and all results obtained should be reported to
                               georgii@mathematik.uni-muenchen.de
   Publications of results must contain a reference to the authors of this program.

Warning:
 - The program was only tested under MacOS 8.X

Bug-Report:
 - Report any bugs to the email address above. 

Description:
The program implements a Gibbs sampler of Propp-Wilson type (coupling from the past) 
producing perfect samples from the continuum Ising model. 
This model consists of particles of two types, plus or minus, with a soft intertype 
repulsion and no interaction between particles of the same type. 
The intertype potential is predefined as
               J(x-y)= (1-|x-y|)^2 for |x-y|<1, and J(x-y)=0 otherwise. 
You may choose
 - its prefactor ß>0 (the inverse temperature), 
 - the activity z>0 (the a priori density of each type of particles)
 - the linear size L of the window (integer valued)
 - the boundary condition: 
          plus (fixed Poisson sample of plus particles outside of the window), 
          free (no particle off the window), or 
          periodic (the window forms a torus).

On the screen you see the plus- and minus-particles for two processes evolving 
simultaneously with maximal resp. minimal initial condition. 
(Note: maximality and minimality refers to the ordering which is increasing in the plus 
particles and decreasing in the minus particles.)
The following color code is used:
 - blue = plus particles in the minimal process
 - red = minus particles in the maximal process
 - cyan = plus particles in the difference of maximal and minimal process
 - magenta = minus particles in the difference of minimal and maximal process

You also get information on the number or particles of the extremal processes
after each run from a negative time to time 0, so that you see the progress of
coalescence.
 -  NXmax  resp. NXmin = number of plus particles in the maximal resp. minimal 	
		 process
 -  NYmax  resp. NYmin = number of minus particles in the maximal resp. minimal 
		 process
After a random time the minimal and the maximal process coalesce and have the 
correct distribution. The particle sample and its random-cluster representation are shown.

For more mathematical and physical background you should consult the survey paper
     ` Phase transition and percolation in Gibbsian particle models '
                   by Hans-Otto Georgii, University of Munich,
which you can download from the website
		 http://www.mathematik.uni-muenchen.de/~georgii/CIsing.html
The latest version of this program can also be found there. 

© by Hans-Otto and Joachim Georgii