#at the start of the program it needs a parameter file of this structure.
#with linux the command line reads: ./laplaceeq infilepath.in
#In the following the parameters are explained:
A18e 				     				# this is a tag which is included in the outputfile name.
/home/horch/workspace/theo5_numerik/ 	# absolute directory for the output
jacobi				     				# method used for the solution of the laplace equation.
										# possible options are: 'jacobi', 'red-black' or 'gauss-seidel'
X 200									# extent in x-range for the finest lattice
Y 200									# extent in y-range for the finest lattice
F 2										# Factor between the coarser lattice to the next finer step.
x 50									# extent in x-range for the coarsest lattice
y 50									# extent in y-range for the coarsest lattice
										# the next finer lattice to be calculated after this
										# would be (x'=x*F, y'=y*)F = (100, 100)
NP 100									# this parameter is either the number of iterations if (NP>1.) 
										# or the precision if (NP<1.), the precision is given by the 
										# absolute of the maximum change from one step to the next.
npotential 2							# number of potentials to be defined. keep in mind that if these
										# definitions overlap only the last definition of the overlapping points
										# is used in the calculation.	
0 2 0 2 10.								# the parameters are organized as: x1, x2, y1, y2, value of the potential (double precision)
0 2 8 9 -10.							# => each potential is constructed as a rectangle, a line if x1=x2 or y1=y2, or one lattice site only 
										# if x1=x2 and y1=y2. 
nground 1								# number of grounded areas to be defined. the same rules for the overlap apply.
										# also: the methods gauss-seidel and red-black are disabled for grounded areas
										# since no convergence was achieved for these methods. this may be due to their
										# update process.
25 40 25 40								# again the parameters are organized as: x1, x2, y1, y2 creating a rectangle, line, or point (which would
										# be quite useless).
plot 1									# there are two possible options here:
										# 1: the program creates plots directly from the computed data and removes these temporary files after plotting.
										# for this option to work you need gnuplot to create the plots and latex for postprocessing on a LINUX
										# system.
										# 0: (or anything else but 1) the data files are the only output here and you have to generate plots
										# manually.
############################################################################################################################################
Example files for the exercises are included as a18fi1.in, ... . To start the program you may either use the already 
compiled executable in '/theo5_numerik/A18f/laplaceeq' or compile the program yourself by typing 'make' in '/theo5_numerik/main/'. In order
to compile the program you need an mpi-compiler. There are many different versions available but since only the function MPI_Wtime() and 
MPI_Init() are used any version should do. You may also need to adapt the Makefile in '/theo5_numerik/main/Makefile' to your installation
of MPI.

Should you have any questions about the program or hints for further improvements contact me via email: horch@kph.uni-mainz.de