Program options

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Program options

The simulation program takes most of its parameters as command line arguments. Rather than build a complicated configuration file, a command script is used to invoke the simulation with the appropriate options, and then perform whatever post-processing is required.

The Getopt(3) routine supplied with the G++ library is used to parse the options in a standard way. The program understands the following options:

fakeDistribution Produces an initial spatial distribution that has all the quarks lined on the X axis. The first quark is at position , with additional quarks at intervals of . ( is the size of the periodic box, here is the total number of particles.) The effect of this distribution is to evenly space the quarks along the middle of the X axis. This option predates the -D option.
Produces an initial spatial distribution that is limited to the X-axis (). The X positions are random.
Produces an initial spatial distribution that is limited to the X-Y plane (). The X and Y positions are random.
Produces an initial spatial distribution with all three components random.
-D filename
Reads the initial spatial and velocity values from a file (provided as an argument). The file consists of lines of six numbers each. The order for each line is . The order of the lines is followed by . For example: arrange3Periodic boundary conditions with 1-D test arrangement produces the arrangement shown in figure .

-a side
sets the size of the arena. The arena is the volume inside the periodic boundary box, in which the particles can interact. The argument is a number, and determines the size of the box. The arena will be in size.

-E stop-time
The time at which to stop the simulation. Also sets the termination condition to be time based.

-f forceCoeff
sets the magnitude of the force coefficient ( in equation ). Default value is GeV.

-F frictionCoeff
sets the magnitude of the linear friction term. By default it is zero.

-G seed
initializes the random number generator with this value. It must be an integer.
-i iterations
sets the number of step iterations that the simulation should run for. If both -i and -E are given, the last one determines when the simulation will terminate. The combination does not produce an or-condition.
-n num-quarks
determines how many pairs of quarks will be simulated. Must be an integer.
-o filename
sets the basename of the output data file. If now extension is given, then the extension .raw is added.

-r record-interval
sets the interval (in time units) between entries to the data file.

-R start-time
the data file will not be written until at least start-time has passed. By default, this is zero.

-t temperature
sets the temperature for the Boltzman distribution of initial velocities. This option is accepted, but currently has no affect.

increases the verbose flag by one. The verbose determines how much debugging the program will produce. By default it produces no debugging. The Unix signals SIGUSR1 ( SIGUSR2) can be sent to the simulation process to increase (decrease) the verbose flag by one. This is useful to determine if the simulation has gotten stuck, or if it just slow.

-S largest-step
sets the largest step size which will be allowed. Default is 10000. (See the section )

-z epsilon
sets the tolerance used to determine if two results are equal in the integration routine. Value is a percentage by which the two results may differ. By default it is

-s smallest-step
sets the smallest step size which will be allowed. Default is 1. (See the section )