Home > Legacy archive > User’s manual > Switches

The switches are used at runtime, by invoking fargo on the command line, to give some information or to modify its behavior.


or, if fargo is not in your path, but is in your current working directory:

where input_file.par is an ascii file that contains all the parameters for the run (see the list of parameters).

A brief description of the switches is given on the standard output by invoking fargo without any argument.

The switches list is the following:

-a every DT, the mesh mass and angular momentum are written to the standard output.
-b Initialize properly the azimuthal velocity so that the centrifugal balance is enforced to the platform accuracy, regardless of the resolution (the method to do that is described in Masset & Ogilvie 2004, ApJ, 615, 1000, in section 2.4).
-c Sloppy CFL condition. The CFL timestep limit is usually checked after every hydro timestep. There may be many such timesteps over a time interval DT. If the -c flag is set, the CFL timestep limit is evaluated only every DT. This may be relevant for low to medium mass planet with reasonnable smoothing lengths, which do not strongly perturb the flow.
-d Print some debugging information on the standard output after every timestep, which gives the CFL most restricting zone and the reason for the limit (advection speed, sound speed, viscosity or shear).
-e Activate EU test problem torque file output and wave damping boundary conditions.
-f scaling Scale the density array by `scaling’ before running. It may be used during a restart to get a lighter or heavier disk. It can not be used twice for two consecutive restarts.
-i The unperturbed surface density profile is sometimes needed by the code (e.g. to impose the surface density at the boundaries for the non-reflecting boundary condition). When setting the -i flag, instead of using the analytic profile given by Sigma0, SigmaProfile and possibly CavityRadius and CavityRatio, the code uses the surface density profile at restart as the reference.
-m Merge output from different processes (MPI only). Unless each processor has a different filesystem and does not see the other processors filesystems, you should use this flag. The output is then strictly similar to a sequential run output.
-n Do not start a run. Just read the parameter file, output any information possibly provided by other switches (such as -v), and quit.
-o outputdir Overrides the output directory specified by the parameter file variable Outputdir.
-p Give some basic profiling information every DT.
-s number Restart simulation, using output #number as initial conditions.
-t Provide some CPU usage information at each output. You can deduce an estimate of the total CPU consumption of a run by extrapolating the indications at the begining. Remember however that especially with the FARGO algorithm the time step may be strongly variable with time.
-v Verbose mode. Some information is provided before the run starts, including expected disk usage, some physical properties of the disk, etc. Note that some of this information is obsolete, and may be inaccurate.
-z Fake sequential run. Cumulative operation in MPI (such as torque integral over the mesh) may give slightly different results in sequential and MPI calculations, due to the random ordering of the sum terms in this last case. Using the -z flag in an MPI calculation ensures that the sum result is strictly the same as for a sequential run.
-(0-9) Write initial (or restart) HD variables and proceed to nth following output, then quit. The number of outputs provided by the parameter file variables Ntot and Ninterm is therefore discarded (although Ninterm is used to proceed between successive outputs). This option must stand alone on one switch (-va -4 is legal, -v4a is not).

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