Enzo Parameter List

Editors: Please note the dictionary format of the parameters, and help to edit the list to match the stopping parameters example.

The following is a largely complete list of the parameters that enzo understands, and a brief description of what they mean. They are grouped roughly by meaning; an alphabetical list is also available. Parameters for individual test problems are also listed here.

This parameter list has two purposes. The first is to describe and explain the parameters that can be put into the initial parameter file that begins a run. The second is to provide a comprehensive list of all parameters that the code uses, including those that go into an output file (which contains a complete list of all parameters), so that users can better understand these output files.

The parameters fall into a number of categories:

external

These are user parameters in the sense that they can be set in the parameter file, and provide the primary means of communication between the enzo and the user.

internal

These are mostly not set in the parameter file (although strictly speaking they can be) and are generally used for program to communicate with itself (via the restart of output files).

obsolete

No longer used.

reserved

To be used later.

Generally the external parameters are the only ones that are modified or set, but the internal parameters can provide useful information and can sometimes be modified so I list them here as well. Some parameters are true/false or on/off boolean flags. Eventually, these may be parsed, but in the meantime, I use the common convention of 0 meaning false or off and 1 for true or on.

This list includes parameters for current version as of February 2004 (the revision number v1_0_0).

Stopping Parameters

StopTime (external)

This parameter specifies the time (in code units) when the calculation will halt. For cosmology simulations, this variable is automatically set by CosmologyFinalRedshift. No default.

StopCycle (external)

The cycle (top grid timestep) at which the calculation stops. A value of zero indicates that this criterion is not be used. Default: 0

StopFirstTimeAtLevel (external)

Causes the simulation to immediately stop when a specified level is reached. Default value 0 (off), possible values are levels 1 through maximum number of levels in a given simulation.

StopCPUTime

Reserved for future use.

Initialization Parameters

• ProblemType (external) - This integer specifies the type of problem to be run. It's value causes the correct problem initializer to be called to set up the grid, and also may trigger certain boundary conditions or other problem-dependent routines to be called. The possible values are listed below. [Not all of these problems run with more than one processor. The list of those known to work in parallel are: 23, 25, 30.] Default: none. For other problem-specific parameters follow the links below.

1 - Shock Tube	20 - Zeldovich Pancake	25 - Test Gravity: Sphere
2 - Wave Pool	21 - Pressureless Collapse	26 - Gravity Equilibrium Test
3 - Shock Pool	22 - Adiabatic Expansion	27 - Collapse Test
4 - Double Mach Reflection	23 - Test Gravity	30 - Cosmology Simulation
5 - Shock In A Box	24 - Spherical Infall	40 - Supernova Restart

• TopGridRank (external) - This specified the dimensionality of the root grid and by extension the entire hierarchy. It should be 1,2 or 3. Default: none
• TopGridDimensions (external) - This is the dimension of the top or root grid. It should consist of 1, 2 or 3 integers separated by spaces. For those familiar with the KRONOS or ZEUS method of specifying dimensions, these values do not include ghost or boundary zones. A dimension cannot be less than 3 zones wide and more than MAX_ANY_SINGLE_DIRECTION - NumberOfGhostZones*2. MAX_ANY_SINGLE_DIRECTION is defined in fortran.def. Default: none

• DomainLeftEdge, DomainRightEdge (external) - These float values specify the two corners of the problem domain (in code units). The defaults are: 0 0 0 for the left edge and 1 1 1 for the right edge.
• LeftFaceBoundaryCondition, RightFaceBoundaryCondition (external) - These two parameters each consist of vectors of integers (of length TopGridRank). They specify the boundary conditions for the top grid (and hence the entire hierarchy). The first integer corresponds to the x-direction, the second to the y-direction and the third, the z-direction. The possible values are: 0 - reflecting, 1 - outflow, 2 - inflow, 3 - periodic. For inflow, the inflow values can be set through the next parameter, or more commonly are controlled by problem-specific code triggered by the ProblemType. Default: 0 0 0
• BoundaryConditionName (external) - While the above parameters provide an easy way to set an entire side of grid to a given boundary value, the possibility exists to set the boundary conditions on an individual cell basis. This is most often done with problem specific code, but it can also be set by specifying a file which contains the information in the appropriate format. This is too involved to go into here. Default: none
• InitialTime (internal) - The time, in "code" units, of the current step. For cosmology the units are in free-fall times at the initial epoch (see output format). Default: generally 0, depends on problem
• Initialdt (internal) - The timestep, in "code" units, for the current step. For cosmology the units are in free-fall times at the initial epoch (see output format). Default: generally 0, depends on problem
• GridVelocity (obsolete) - For problems in which the grid must move. Originally implemented, but was never used, and so almost surely doesn't work. Default: 0 0 0

I/O Parameters

There are three ways to specify the frequency of outputs: time-based, cycle-based (a cycle is a top-grid timestep), and, for cosmology simulations, redshift-based. There is also a shortened output format intended for visualization (movie format).

• dtDataDump (external) - The time interval, in code units, between time-based outputs. A value of 0 turns off the time-based outputs. Default: 0
• CycleSkipDataDump (external) - The number of cycles (top grid timesteps) between cycle-based outputs. Zero turns off the cycle-based outputs. Default: 0
• DataDumpName (external) - The base file name used for both time and cycle based outputs. Default: data
• RedshiftDumpName (external) - The base file name used for redshift-based outputs (this can be overridden by the CosmologyOutputRedshiftName parameter). Normally a four digit identification number is appended to the end of this name, starting from 0000 and incrementing by one for every output. This can be over-ridden by including four consecutive R's in the name (e.g. RedshiftRRRR) in which case the an identification number will not be appended but the four R's will be converted to a redshift with an implied decimal point in the middle (i.e. z=1.24 becomes 0124). Default: RedshiftOutput
• CosmologyOutputRedshift[NNNN] (external) - The time and cycle-based outputs occur regularly at constant intervals, but the redshift outputs are specified individually. This is done by the use of this statement, which sets the output redshift for a specific identification number (this integer is between 0000 and 9999 and is used in forming the name). So the statement CosmologyOutputRedshift[1] = 4.0 will cause an output to be written out at z=4 with the name RedshiftOutput0001 (unless the base name is changed either with the previous parameter or the next one). This parameter can be repeated with different values for the number (NNNN) Default: none
• CosmologyOutputRedshiftName[NNNN] (external) - This parameter overrides the parameter RedshiftOutputName for this (only only this) redshift output. Can be used repeatedly in the same manner as the previous parameter. Default: none
• dtMovieDump (external) - The time interval, in code units, between movie dumps. A value of 0 turns off the movie dumps. Default: 0
• MovieRegionLeftEdge, MovieRegionRightEdge (external) - These two parameters control the region for which movie dumps are made. When a movie dump is generated (see the section on output format), only those grid points and particles within this region are written out to the movie data files.
• MovieDumpName (external) - This character parameter is the base name of the movie dumps. Default: MovieData
• OutputFirstTimeAtLevel (external) - This forces enzo to output when a given level is reached, and at every level thereafter. Default is 0 (off). User can usefully specify anything up to the maximum number of levels in a given simulation.
• XrayLowerCutoffkeV, XrayUpperCutoffkeV, XrayTableFileName, (external) - These parameters are used in 2D projections (enzo -p ...). The first two specify the X-ray band (observed at z=0) to be used, and the last gives the name of an ascii file that contains the X-ray spectral information. A gzipped version of this file good for bands within the 0.1 - 20 keV range is available here. If these parameters are specified, then the second field is replaced with integrated emissivity along the line of sight in units of 10^{-23 erg/cm}2/s.
• ExtractFieldsOnly (external) - Used for extractions (enzo -x ...) when only field data are needed instead of field + particle data. Default is 1 (TRUE).
• dtRestartDump - Reserved for future use.
• dtHistoryDump - Reserved for future use.
• CycleSkipRestartDump - Reserved for future use.
• CycleSkipHistoryDump - Reserved for future use.
• RestartDumpName - Reserved for future use.
• HistoryDumpName - Reserved for future use.
• ParallelRootGridIO (external) - Normally, for the mpi version, the root grid is read into the root processor and then partitioned to separate processors. However, for very large root grids (e.g. 512³), the root processor may not have enough memory. If this toggle switch is set on (i.e. to the value 1), then each processor reads its own section of the root grid. More I/O is required (to split up the grids and particles), but it is more balanced in terms of memory. ParallelRootGridIO and ParallelParticleIO MUST be set to 1 (TRUE) for runs involving > 64 cpus! Default: 0 (FALSE). See also Unigrid below.
• Unigrid (external) - This parameter must be set to 1 (TRUE) in order to enable some modifications which prevent process 0 from instantiating a (useless) copy of a top grid sized field. Must be set TRUE for unigrid runs with ParallelRootGridIO = 1 so that large simulations would start on distributed-memory systems. Default: 0 (FALSE)

Hierarchy Control Parameters

• StaticHierarchy (external) - A flag which indicates if the hierarchy is static (1) or dynamic (0). In other words, a value of 1 takes the a out of amr. Default: 1
• RefineBy (external) - This is the refinement factor between a grid and it's subgrid. For cosmology simulations, I have found the number 2 to be most useful. Default: 4
• MaximumRefinementLevel (external) - This is the lowest (most refined) depth that the code will produce. It is zero based, so the total number of levels (including the root grid) is one more than this value. Default: 2
• CellFlaggingMethod (external) - The method(s) used to specify when a cell should be refined. This is a list of integers, up to five, as described by the following table. The methods combine in an "OR" fashion: if any of them indicate that a cell should be refined, then it is flagged. For cosmology simulations, methods 2 and 4 are probably most useful. Note that some methods have additional parameters which are described below. Default: 1

        1 - refine by slope 	        5 - refine by baryon overdensity (currently disabled)
        2 - refine by baryon mass 	6 - refine by Jeans length
        3 - refine by shocks 	        7 - refine if cooling time < cell width/sound speed
        4 - refine by particle mass 	
  

• RefineRegionLeftEdge, RefineRegionRightEdge (external) - These two parameters control the region in which refinement is permitted. Each is a vector of floats (of length given by the problem rank) and they specify the two corners of a volume. Default: set equal to DomainLeftEdge and DomainRightEdge.
• MinimumOverDensityForRefinement (external) - These float values (up to 5) are used if the CellFlaggingMethod is 2, 4, or 5 although in slightly different ways. For Method 5, this is the overdensity in terms of (rho/<rho> - 1), where rho is the density of the cell, and <rho> is the mean density. For the others, the meaning is actually just rho/<rho> where rho is the density of the appropriate species. This value is converted into a mass, by multiplying by the volume of the a top grid cell. This result is then stored in the next parameter (unless it is set directly in which case this parameter is ignored), and this defines the mass resolution of the simulation. Note that the volume is of a top grid cell, so if you are doing a multi-grid initialization, you must divide this number by r^(d*l) where r is the refinement factor, d is the dimensionality and l is the (zero-based) lowest level. For example, for a two grid setup where a cell should be refined whenever the mass exceeds 4 times the mean density of the subgrid, this value should be 4 / (2^(3*1)) = 4 / 8 = 0.5. Keep in mind that this parameter has no effect if it is changed in a restart output; if you want to change the refinement mid-run you will have to modify the next parameter. Up to five numbers may be specified here, each corresponding to the respective CellFlaggingMethod. Default: 1.5
• MinimumMassForRefinement (internal) - This float is usually set by the parameter above and so is labeled internal, but it can be set by hand. It is the mass (in units such that the entire mass in the computational volume is 1.0) above which a refinement occurs if the CellFlaggingMethod is appropriately set. There are five numbers here again, as per the above parameter. Default: none
• MinimumMassForRefinementLevelExponent (external). This parameter modifies the behaviour of the above parameter. As it stands, the refinement based on the MinimumMassForRefinement (hereafter Mmin) parameter is complete Lagrangian. However, this can be modified. The actual mass used is Mmin*r^(l*alpha) where r is the refinement factor, l is the level and alpha is the value of this parameter (MinimumMassForRefinementLevelExponent). Therefore a negative value makes the refinement super-Lagrangian, while positive values are sub-Lagrangian. There are up to five values specified here, as per the above two parameters. Default: 0.0
• MinimumSlopeForRefinement (external) - If CellFlaggingMethod is 1, then local gradients are used as the refinement criteria. All variables are examined and the relative slope is computed: abs(q(i+1)-q(i-1))/q(i). Where this value exceeds this parameter, the cell is marked for refinement. This causes problems if q(i) is near zero. This is a single integer (as opposed to the list of five for the above parameters). Default: 0.3
• MinimumPressureJumpForRefinement (external) - If refinement is done by shocks, then this is the minimum (relative) pressure jump in one-dimension to qualify for a shock. The definition is rather standard (see Colella and Woodward's PPM paper for example) Default: 0.33
• MinimumEnergyRatioForRefinement (external) - For the dual energy formalism, and cell flagging by shock-detection, this is an extra filter which removes weak shocks (or noise in the dual energy fields) from triggering the shock detection. Default: 0.1
• FluxCorrection (external) - This flag indicates if the flux fix-up step should be carried out around the boundaries of the sub-grid to preserve conservation (1 - on, 0 - off). Strictly speaking this should always be used, but I have found it to lead to a less accurate solution for cosmological simulations because of the relatively sharp density gradients involved. However, it does appear to be important when radiative cooling is turned on and very dense structures are created (this note added sheepishly in April/99). It does work with the ZEUS hydro method, but since velocity is face-centered, momentum flux is not corrected. Species quantities are not flux corrected directly but are modified to keep the fraction constant based on the density change. Default: 1
• InterpolationMethod (external) - There should be a whole section devoted to the interpolation method, which is used to generate new sub-grids and to fill in the boundary zones of old sub-grids, but a brief summary must suffice. The possible values of this integer flag are shown in the table below. The names specify (in at least a rough sense) the order of the leading error term for a spatial Taylor expansion, as well as a letter for possible variants within that order. The basic problem is that you would like your interpolation method to be: multi-dimensional, accurate, monotonic and conservative. There doesn't appear to be much literature on this, so I've had to experiment. The first one (ThirdOrderA) is time-consuming and probably not all that accurate. The second one (SecondOrderA) is the workhorse: it's only problem is that it is not always symmetric. The next one (SecondOrderB) is a failed experiment, and SecondOrderC is not conservative. FirstOrderA is everything except for accurate. If HydroMethod = 2 (ZEUS), this flag is ignored, and the code automatically uses SecondOrderC for velocities and FirstOrderA for cell-centered quantities. Default: 1

        0 - ThirdOrderA 	3 - SecondOrderC
        1 - SecondOrderA 	4 - FirstOrderA
        2 - SecondOrderB 	
  

• ConservativeInterpolation (external) - This flag (1 - on, 0 - off) indicates if the interpolation should be done in the conserved quantities (e.g. momentum rather than velocity). Ideally, this should be done, but it can cause problems when strong density gradients occur. This must(!) be set off for ZEUS hydro (the code does it automatically). Default: 1
• MinimumEfficiency (external) - When new grids are created during the rebuilding process, each grid is split up by a recursive bisection process that continues until a subgrid is either of a minimum size or has an efficiency higher than this value. The efficiency is the ratio of flagged zones (those requiring refinement) to the total number of zones in the grid. This is a number between 0 and 1 and should probably by around 0.4 for standard three-dimensional runs. Default: 0.2
• NumberOfBufferZones (external) - Each flagged cell, during the regridding process, is surrounded by a number of zones to prevent the phenomenon of interest from leaving the refined region before the next regrid. This integer parameter controls the number required, which should almost always be one. Default: 1
• RefineByJeansLengthSafetyFactor (external) - If the Jeans length refinement criterion (see CellFlaggingMethod) is being used, then this parameter specifies the number of cells which must cover one Jeans length. Default: 4
• StaticRefineRegionLevel[#] (external) - This parameter is used to specify regions of the problem that are to static refined, regardless of other parameters. This is mostly used as an internal mechanism to keep the initial grid hierarchy in place, but can be specified by the user. Up to 20 static regions may be defined (this number set in macros_and_parameters.h), and each static region is labeled starting from zero. For each static refined region, two pieces of information are required: (1) the region (see the next two parameters), and (2) the level at which the refinement is to occurs (0 implies a level 1 region will always exist). Default: none
• StaticRefineRegionLeftEdge[#], StaticRefineRegionRightEdge[#] (external) - These two parameters specify the two corners of a statically refined region (see the previous parameter). Default: none

Hydrodynamic Parameters

• HydroMethod (external) - This integer specifies the hydrodynamics method that will be used. Currently implemented are: 0 - PPM DE (a direct-Eulerian version of PPM), 1 - PPM LR (a Lagrange-Remap version of PPM), 2 - ZEUS (a Cartesian, 3D version of Stone & Norman). The PPM LR version is not recommended. Note that if ZEUS is selected, it automatically turns off ConservativeInterpolation and the DualEnergyFormalism flags. Default: 0
• Gamma (external) - The ratio of specific heats for an ideal gas (used by all hydro methods). If using multiple species (i.e. MultiSpecies > 0), then this value is ignored in favour of a direct calculation (except for PPM LR) Default: 5/3.
• CourantSafetyNumber (external) - This is the maximum fraction of the CFL-implied timestep that will be used to advance any grid. A value greater than 1 is unstable (for all explicit methods). The recommended value is 0.4. Default: 0.6.
• DualEnergyFormalism (external) - The dual energy formalism is needed to make total energy schemes such as PPM DE and PPM LR stable and accurate in the "hyper-Machian" regime (i.e. where the ratio of thermal energy to total energy < ~0.001). Turn on for cosmology runs with PPM DE and PPM LR. Automatically turned off when used with the hydro method ZEUS. Integer flag (0 - off, 1 - on). When turned on, there are two energy fields: total energy and thermal energy. Default: 0
• DualEnergyFormalismEta1, DualEnergyFormalismEta2 (external) - These two parameters are part of the dual energy formalism and should probably not be changed. Defaults: 0.001 and 0.1 respectively.
• PressureFree (external) - A flag that is interpreted by the PPM DE hydro method as an indicator that it should try and mimic a pressure-free fluid. A flag: 1 is on, 0 is off. Default: 0
• PPMFlatteningParameter (external) - This is a PPM parameter to control noise for slowly-moving shocks. It is either on (1) or off (0). Default: 0
• PPMDiffusionParameter (external) - This is the PPM diffusion parameter (see the Colella and Woodward method paper for more details). It is either on (1) or off (0). Default: 1 [Currently disabled (set to 0)]
• PPMSteepeningParameter (external) - A PPM modification designed to sharpen contact discontinuities. It is either on (1) or off (0). Default: 0
• ZEUSQuadraticArtificialViscosity (external) - This is the quadratic artificial viscosity parameter C2 of Stone & Norman, and corresponds (roughly) to the number of zones over which a shock is spread. Default: 2.0
• ZEUSLinearArtificialViscosity (external) - This is the linear artificial viscosity parameter C1 of Stone & Norman. Default: 0.0

Cosmology Parameters

• ComovingCoordinates (external) - Flag (1 - on, 0 - off) that determines if comoving coordinates are used or not. In practice this turns on or off the entire cosmology machinery. Default: 0
• CosmologyFinalRedshift (external) - This parameter specifies the redshift when the calculation will halt. Default: 0.0
• CosmologyOmegaMatterNow (external) - This is the contribution of all non-relativistic matter (including HDM) to the energy density at the current epoch (z=0), relative to the value required to marginally close the universe. It includes dark and baryonic matter. Default: 0.279
• CosmologyOmegaLambdaNow (external) - This is the contribution of the cosmological constant to the energy density at the current epoch, in the same units as above. Default: 0.721
• CosmologyComovingBoxSize (external) - The size of the volume to be simulated in Mpc/h (at z=0). Default: 64.0
• CosmologyHubbleConstantNow (external) - The Hubble constant at z=0, in units of 100 km/s/Mpc. Default: 0.701
• CosmologyInitialRedshift (external) - The redshift for which the initial conditions are to be generated. Default: 20.0
• CosmologyMaxExpansionRate (external) - This float controls the timestep so that cosmological terms are accurate followed. The timestep is constrained so that the relative change in the expansion factor in a step is less than this value. Default: 0.01
• CosmologyCurrentRedshift (information only) - This is not strictly speaking a parameter since it is never interpreted and is only meant to provide information to the user. Default: n/a

Gravity Parameters

• TopGridGravityBoundary (external) - A single integer which specified the type of gravitational boundary conditions for the top grid. Possible values are 0 for periodic and 1 for isolated (for all dimensions). The isolated boundary conditions have not been tested recently, so caveat emptor. Default: 0
• SelfGravity (external) - This flag (1 - on, 0 - off) indicates if the baryons and particles undergo self-gravity.
• GravitationalConstant (external) - This is the gravitational constant to be used. For cgs units it should be 4*pi*G. For cosmology, this value must be 1 for the standard units to hold. Default: 4*pi.
• GreensFunctionMaxNumber (external) - The Green's functions for the gravitational potential depend on the grid size, so they are calculated on a as-needed basis. Since they are often re-used, they can be cached. This integer indicates the number that can be stored. They don't take much memory (only the real part is stored), so a reasonable number is 100. [Ignored in current version]. Default: 1
• GreensFunctionMaxSize - Reserved for future use.
• S2ParticleSize (external) - This is the gravitational softening radius, in cell widths, in terms of the S2 particle described by Hockney and Eastwood in their book Computer Simulation Using Particles. A reasonable value is 3.0. [Ignored in current version]. Default: 3.0
• GravityResolution (external) - This was a mis-guided attempt to provide the capability to increase the resolution of the gravitational mesh. In theory it still works, but has not been recently tested. Besides, it's just not a good idea. The value (a float) indicates the ratio of the gravitational cell width to the baryon cell width. [Ignored in current version]. Default: 1
• ComputePotential (external) - This flag (1 -on, 0 - off) indicates if the gravitational potential is to be computed on the mesh. This is necessary if the energy conservation is to be computed. [not tested] Default: 0
• BaryonSelfGravityApproximation (external) - This flag indicates if baryon density is derived in a strange, expensive but self-consistent way (0 - off), or by a completely reasonable and much faster approximation (1 - on). This is an experiment gone wrong; leave on. Well, actually, it's important for very dense structures as when radiative cooling is turned on, so set to 0 if using many levels and radiative cooling is on [ignored in current version]. Default: 1
• MaximumGravityRefinementLevel (external) - This is the lowest (most refined) depth that a gravitational acceleration field is computed. More refined levels interpolate from this level, provided a mechanism for instituting a minimum gravitational smoothing length. Default: MaximumRefinementLevel (unless HydroMethod is ZEUS and radiative cooling is on, in which case it is MaximumRefinementLevel - 3).
• MaximumParticleRefinementLevel (external) - This is the level at which the dark matter particle contribution to the gravity is smoothed. This works in an inefficient way (it actually smoothes the particle density onto the grid), and so is only intended for highly refined regions which are nearly completely baryon dominated. It is used to remove the discreteness effects of the few remaining dark matter particles. Not used if set to a value less than 0. Default: -1
• PointSourceGravity (external) - This flag (1 - on, 0 - off) indicates if there is to be a (constant) point source gravitational field. Default: 0
• PointSourceGravityConstant (external) - The magnitude of the point source acceleration at a distance of 1 length unit. Default: 1
• PointSourceGravityPosition (external) - If the PointSourceGravity flag is turned on, this parameter specifies the center of the point-source gravitational field. Default: 0 0 0
• UniformGravity (external) - This flag (1 - on, 0 - off) indicates if there is to be a uniform gravitational field. Default: 0
• UniformGravityDirection (external) - This integer is the direction of the uniform gravitational field: 0 - along the x axis, 1 - y axis, 2 - z axis. Default: 0
• UniformGravityConstant (external) - Magnitude (and sign) of the uniform gravitational acceleration. Default: 1

Particle Parameters

• ParticleBoundaryType (external) - The boundary condition imposed on particles. At the moment, this parameter is largely ceremonial as there is only one type implemented: periodic, indicated by a 0 value. Default: 0
• ParticleCourantSafetyNumber (external) - This somewhat strangely named parameter is the maximum fraction of a cell width that a particle is allowed to travel per timestep (i.e. it is a constant on the timestep somewhat along the lines of it's hydrodynamic brother). Default: 0.5
• NumberOfParticles (obsolete) - Currently ignored by all initializers, except for TestGravity and TestGravitySphere where it is the number of test points. Default: 0
• NumberOfParticleAttributes (internal) - It is set to 3 if either StarParticleCreation or StarParticleFeedback is set to 1 (TRUE). Default: 0
• ParallelParticleIO (external) - Normally, for the mpi version, the particle data are read into the root processor and then distributed to separate processors. However, for very large number of particles, the root processor may not have enough memory. If this toggle switch is set on (i.e. to the value 1), then Ring i/o is turned on and each processor reads its own part of the particle data. More I/O is required, but it is more balanced in terms of memory. ParallelRootGridIO and ParallelParticleIO MUST be set for runs involving > 64 cpus! Default: 0 (FALSE).

Parameters for Additional Physics

• RadiativeCooling (external) - This flag (1 - on, 0 - off) controls whether or not a radiative cooling module is called for each grid. There are currently two possibilities, controlled by the value of another flag. If the MultiSpecies flag is off, then equilibrium cooling is assumed, and a file called cool_rates.in is read to set a cooling curve. This file consists of a set of temperature and the associated cgs cooling rate; a sample compute with a metallicity Z=0.3 Raymond-Smith code is provided in amr_mpi/exe/cool_rates.in. If the MultiSpecies flag is on, then the cooling rate is computed directly by the species abundances. This routine (which uses a backward differenced multi-step algorithm) was plundered from the Hercules code written by Peter Anninos and Yu Zhang, featuring rates from Tom Abel. Default: 0
• MultiSpecies (external) - If this flag (1, 2, 3- on, 0 - off) is on, then the code follows not just the total density, but also the ionization states of Hydrogen and Helium. If set to 2, then a nine-species model (including H2, H2+ and H-) will be computed, otherwise only six species are followed (H, H+, He, He+, He++, e-). If set to 3, then a 12 species model is followed, including D, D+ and HD. This routine, like the last one, is based on work done by Abel, Zhang and Anninos. Default: 0
• GadgetEquilibriumCooling (external) - An implementation of the ionization equilibrium cooling code used in the GADGETcode which includes both radiative cooling and a uniform metagalactic UV background specified by the TREECOOL file (in the amr_mpi/exe directory). When this parameter is turned on, MultiSpecies and RadiationFieldType are forced to 0 and RadiativeCooling is forced to 1.

[Not in public release version]

• MultiMetals (external) - This was added so that the user could turn on or off additional metal fields - currently there is the standard metallicity field (Metal_Density) and two additional metal fields (Z_Field1 and Z_Field2). Acceptable values are 1 or 0, default 0 (off).
• StarParticleCreation (external) - If set to 1 or 2, then one of two possible, experimental, star formation algorithms is used. The algorithms are from Cen & Ostriker (1992) and the implementation is by Chris Loken, Brian O'Shea and GLB. The second algorithm (2) is recommended. Defaut: 0
• StarParticleFeedback (external) - If set to 1 or 2, then one of two possible star feedback algorithms is used. The second (StarParticleFeedback = 2) is recommended. Default: 0
• StarMakerOverDensityThreshold (external) - The overdensity threshold (relative to the total mean density, not just the dark matter mean density) before star formation will be considered. Default: 100
• StarMakerMassEfficiency (external) - The fraction of identified baryonic mass in a cell (Mass*dt/t_dyn) that is converted into a star particle. Default: 1
• StarMakerMinimumMass (external) - The minimum mass of star particle, in solar masses. Note however, the star maker algorithm 2 has a "stochastic" star formation algorithm that will, in a pseudo-random fashion, allow star formation even for very low star formation rates. It attempts to do so (relatively successfully according to tests) in a fashion that conserves the global average star formation rate. Default: 1e9
• StarMakerMinimumDynamicalTime (external) - When the star formation rate is computed, the rate is proportional to M_baryon * dt/max(t_dyn, t_max) where t_max is this parameter. This effectively sets a limit on the rate of star formation based on the idea that stars have a non-negligible formation and life-time. The unit is years. Default: 1e6
• StarMassEjectionFraction (external) - The mass fraction of created stars which is returned to the gas phase. Default: 0.25
• StarMetalYield (external) - The mass fraction of metals produced by each unit mass of stars created (i.e. it is multiplied by mstar, not ejected). Default: 0.02
• StarEnergyToThermalFeedback (external) - The fraction of the rest-mass energy of the stars created which is returned to the gas phase as thermal energy. Default: 1e-5
• StarEnergyToStellarUV (external) - The fraction of the rest-mass energy of the stars created which is returned as UV radiation with a young star spectrum. Default: 3e-6
• StarEnergyToQuasarUV (external) - The fraction of the rest-mass energy of the stars created which is returned as UV radiation with a quasar spectrum. Default: 5e-6
• RadiationFieldType (external) - This integer parameter specifies the type of radiation field that is to be used. It can currently only be used if MultiSpecies = 1 (i.e. no molecular H support). The following values are used: (1) - Haardt & Madau spectrum with q_alpha=-1.5; (2) - Haardt & Madau spectrum with q_alpha = -1.8; (3) - reserved for experimentation; (4) - H&M spectrum (q_alpha=-1.5) supplemented with an X-ray Compton heating background from Madau & Efstathiou (see astro-ph/9902080); (9) - a constant molecular H2 photo-dissociation rate; (10) - internally computed radiation field using the algorithm of Cen & Ostriker; (11) - same as previous, but with very, very simple optical shielding fudge. Default: 0
• RadiationFieldLevelRecompute (external) - This integer parameter is used only if the previous parameter is set to 10 or 11. It controls how often (i.e. the level at which) the internal radiation field is recomputed. Default: 0
• RadiationSpectrumNormalization (external) - This parameter was initially used to normalize the photo-ionization and photo-heating rates computed in the RadiationFieldCalculateRates() and then passed on to calc_photo_rates(), calc_rad() and calc_rates() routines. Later, the normalization as a separate input parameter was dropped for all cases by using the rates computed in RadiationFieldCalculateRates() with one exception: The molecular hydrogen (H2) dissociation rate. There a normalization is performed on the rate by multiplying it with RadiationSpectrumNormalization. Default:
• UseMinimumPressureSupport (external) - When radiative cooling is turned on, and objects are allowed to collapse to very small sizes (i.e. a few cells), and they are evolved for many, many dynamical times, then unfortunate things happen. Primarily, there is some spurious angular momentum generation, and possible some resulting momentum non-conservation. To alleviate this problem, a very simple fudge was introduced: if this flag is turned on, then a minimum temperature is applied to grids with level == MaximumRefinementLevel. This minimum temperature is that required to make each cell Jeans stable multiplied by the parameter below. If you use this, it is advisable to also set the gravitational smoothing length in the form of MaximumGravityRefineLevel to 2 or 3 less than MaximumRefinementLevel. Default: 0
• MinimumPressureSupportParameter (external) - This is the parameter alluded to above. Very roughly speaking, is is the number of cells over which a gravitationally bound small cold clump, on the most refined level, will be spread over. Default: 100

Test Problem Parameters

Shock Tube (1: unigrid and AMR)

Riemann problem or arbitrary discontinuity breakup problem. The discontinuity initially separates two arbitrary constant states: Left and Right. Default values correspond to the so called Sod Shock Tube setup (test 1.1). A table below contains a series of recommended 1D tests for hydrodynamic method, specifically designed to test the performance of the Riemann solver, the treatment of shock waves, contact discontinuities, and rarefaction waves in a variety of situations (Toro 1999, p. 129).

      Test 	LeftDensity 	LeftVelocity 	LeftPressure 	RightDensity 	RightVelocity 	RightPressure
      1.1 	1.0 	        0.0 	        1.0 	        0.125 	        0.0 	        0.1
      1.2 	1.0 	        -2.0 	        0.4 	        1.0 	        2.0 	        0.4
      1.3 	1.0 	        0.0 	        1000.0          1.0 	        0.0 	        0.01
      1.4 	1.0 	        0.0 	        0.01 	        1.0 	        0.0 	        100.0
      1.5 	5.99924 	19.5975 	460.894 	5.99242 	-6.19633 	46.0950

• ShockTubeBoundary (external) - Discontinuity position. Default: 0.5
• ShockTubeDirection (external) - Discontinuity orientation. Type: integer. Default: 0 (shock(s) will propagate in x-direction)
• ShockTubeLeftDensity, ShockTubeRightDensity (external) - The initial gas density to the left and to the right of the discontinuity. Default: 1.0 and 0.125, respectively
• ShockTubeLeftVelocity, ShockTubeRightVelocity (external) - The same as above but for the velocity component in ShockTubeDirection. Default: 0.0, 0.0
• ShockTubeLeftPressure, ShockTubeRightPressure (external) - The same as above but for pressure. Default: 1.0, 0.1

Wave Pool (2)

Wave Pool sets up a simulation with a 1D sinusoidal wave entering from the left boundary. The initial active region is uniform and the wave is entered via inflow boundary conditions.

• WavePoolAmplitude (external) - The amplitude of the wave. Default: 0.01 - a linear wave.
• WavePoolAngle (external) - Direction of wave propagation with respect to x-axis. Default: 0.0
• WavePoolDensity (external) - Uniform gas density in the pool. Default: 1.0
• WavePoolNumberOfWaves (external) - The test initialization will work for one wave only. Default: 1
• WavePoolPressure (external) - Uniform gas pressure in the pool. Default: 1.0
• WavePoolSubgridLeft, WavePoolSubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no subgrids)
• WavePoolVelocity1(2,3) (external) - x-,y-, and z-velocities. Default: 0.0 (for all)
• WavePoolWavelength (external) - The wavelength. Default: 0.1 (one-tenth of the box)

Shock Pool (3: unigrid 2D, AMR 2D and unigrid 3D)

The Shock Pool test sets up a system which introduces a shock from the left boundary. The initial active region is uniform, and the shock wave enters via inflow boundary conditions. 2D and 3D versions available. (D. Mihalas & B.W. Mihalas, Foundations of Radiation Hydrodynamics, 1984, p. 236, eq. 56-40.)

• ShockPoolAngle (external) - Direction of the shock wave propagation with respect to x-axis. Default: 0.0
• ShockPoolDensity (external) - Uniform gas density in the preshock region. Default: 1.0
• ShockPoolPressure (external) - Uniform gas pressure in the preshock region. Default: 1.0
• ShockPoolMachNumber (external) - The ratio of the shock velocity and the preshock sound speed. Default: 2.0
• ShockPoolSubgridLeft, ShockPoolSubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no subgrids)
• ShockPoolVelocity1(2,3) (external) - Preshock gas velocity (the Mach number definition above assumes a zero velocity in the laboratory reference frame. Default: 0.0 (for all components)

Double Mach Reflection (4)

A test for double Mach reflection of a strong shock (Woodward & Colella 1984). Most of the parameters are "hardwired": d0 = 8.0, e0 = 291.25, u0 = 8.25*sqrt(3.0)/2.0, v0 = -8.25*0.5, w0 = 0.0

• DoubleMachSubgridLeft (external) - Start position of the subgrid. Default: 0.0
• DoubleMachSubgridRight (external) - End positions of the subgrid. Default: 0.0

Shock in a Box (5)

A stationary shock front in a static 3D subgrid (Anninos et al. 1994). Initialization is done as in the Shock Tube test.

• ShockInABoxBoundary (external) - Position of the shock. Default: 0.5
• ShockInABoxLeftDensity, ShockInABoxRightDensity (external) - Densities to the Right and to the Left of the shock front. Default: dL=1.0 and dR = dL*((Gamma+1)*m*m)/((Gamma-1)*m*m + 2), where m=2.0.
• ShockInABoxLeftVelocity, ShockInABoxRightVelocity (external) - Velocities to the Right and to the Left of the shock front. Default: vL=shockspeed and vR=shockspeed-m*sqrt(Gamma*pL/dL)*(1-dL/dR), where m=2.0, shockspeed=0.9*sqrt(Gamma*pL/dL)*m.
• ShockInABoxLeftPressure, ShockInABoxRightPressure (external) - Pressures to the Right and to the Left of the shock front. Default: pL=1.0 and pR=pL*(2.0*Gamma*m*m - (Gamma-1))/(Gamma+1), where m=2.0.
• ShockInABoxSubgridLeft, ShockInABoxSubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 (for both)

Zeldovich Pancake (20)

A test for gas dynamics, expansion terms and self-gravity in both linear and non-linear regimes [Brian et al. (1995), Sect. 3.4-3.5; Norman & Brian (1998), Sect. 4]

• ZeldovichPancakeCentralOffset (external) - Offset of the pancake plane. Default: 0.0 (no offset)
• ZeldovichPancakeCollapseRedshift (external) - A free parameter which determines the epoch of caustic formation. Default: 1.0
• ZeldovichPancakeDirection (external) - Orientation of the pancake. Type: integer. Default: 0 (along the x-axis)
• ZeldovichPancakeInitialTemperature (external) - Initial gas temperature. Units: degrees Kelvin. Default: 100
• ZeldovichPancakeOmegaBaryonNow (external) - Omega Baryon at redshift z=0; standard setting. Default: 1.0
• ZeldovichPancakeOmegaCDMNow (external) - Omega CDM at redshift z=0. Default: 0 (assumes no dark matter)

Pressureless Collapse (21)

An 1D AMR test for the gravity solver and advection routines: the two-sided one-dimensional collapse of a homogeneous plane parallel cloud in Cartesian coordinates. Isolated boundary conditions. Gravitational constant G=1; free fall time 0.399. The expansion terms are not used in this test. (Brian et al. 1995, Sect. 3.1).

• PressurelessCollapseDirection (external) - Coordinate direction. Default: 0 (along the x-axis).
• PressurelessCollapseInitialDensity (external) - Initial density (the fluid starts at rest). Default: 1.0
• PressurelessCollapseNumberOfCells (external) - ???. Default: GridDimension[PressurelessCollapseDirection] - 2

Adiabatic Expansion (22)

A test for time-integration accuracy of the expansion terms (Brian et al. 1995, Sect. 3.3).

• AdiabaticExpansionInitialTemperature (external) - Initial temperature for Adiabatic Expansion test; test example assumes 1000 K. Default: 200. Units: degrees Kelvin
• AdiabaticExpansionInitialVelocity (external) - Initial expansion velocity. Default: 100. Units: km/s
• AdiabaticExpansionOmegaBaryonNow (external) - Omega Baryon at redshift z=0; standard value 1.0. Default: 1.0
• AdiabaticExpansionOmegaCDMNow (external) - Omega CDM at redshift z=0; default setting assumes no dark matter. Default: 0.0

Test Gravity (23)

We set up a system in which there is one grid point with mass in order to see the resulting acceleration field. If finer grids are specified, the mass is one grid point on the subgrid as well. Periodic boundary conditions are imposed (gravity).

• TestGravityDensity (external) - Density of the central peak. Default: 1.0
• TestGravityMotionParticleVelocity (external) - Initial velocity of test particle(s) in x-direction. Default: 1.0
• TestGravityNumberOfParticles (external) - The number of test particles of a unit mass. Default: 0
• TestGravitySubgridLeft, TestGravitySubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no subgrids)
• TestGravityUseBaryons (external) - Boolean switch. Type: integer. Default: 0 (FALSE)

Spherical Infall (24)

A test based on Bertschinger's (1985) 3D self-similar spherical infall solution onto an initially overdense perturbation in an Einstein-de Sitter universe.

• SphericalInfallCenter (external) - Coordinate(s) for the accretion center. Default: top grid center
• SphericalInfallFixedAcceleration (external) - Boolean flag. Type: integer. Default: 0 (FALSE)
• SphericalInfallFixedMass (external) - ???. Default: If SphericalInfallFixedMass is undefined and SphericalInfallFixedAcceleration==TRUE, then SphericalInfallFixedMass = SphericalInfallInitialPerturbation*TopGridVolume
• SphericalInfallInitialPerturbation (external) - The perturbation of initial mass density. Default: 0.1
• SphericalInfallOmegaBaryonNow (external) - Omega Baryon at redshift z=0; standard setting. Default: 1.0
• SphericalInfallOmegaCDMNow (external) - Omega CDM at redshift z=0. Default: 0.0 (assumes no dark matter) Default: 0.0
• SphericalInfallSubgridIsStatic (external) - Boolean flag. Type: integer. Default: 0 (FALSE)
• SphericalInfallSubgridLeft, SphericalInfallSubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no subgrids)
• SphericalInfallUseBaryons (external) - Boolean flag. Type: integer. Default: 1 (TRUE)

Test Gravity: Sphere (25)

Sets up a 3D spherical mass distribution and follows its evolution to test the gravity solver.

• TestGravitySphereCenter (external) - The position of the sphere center. Default: at the center of the domain
• TestGravitySphereExteriorDensity (external) - The mass density outside the sphere. Default: tiny_number
• TestGravitySphereInteriorDensity (external) - The mass density at the sphere center. Default: 1.0
• TestGravitySphereRadius (external) - Radius of self-gravitating sphere. Default: 0.1
• TestGravitySphereRefineAtStart (external) - Boolean flag. Type: integer. Default: 0 (FALSE)
• TestGravitySphereSubgridLeft, TestGravitySphereSubgridRight (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no subgrids)
• TestGravitySphereType (external) - Type of mass density distribution within the sphere. Options include: (0) uniform density distrubution within the sphere radius; (1) a power law with an index -2.0; (2) a power law with an index -2.25 (the exact power law form is, e.g., r^-2.25, where r is measured in units of TestGravitySphereRadius). Default: 0 (uniform density)
• TestGravitySphereUseBaryons (external) - Boolean flag. Type: integer . Default: 1 (TRUE)

Gravity Equilibrium Test (26)

Sets up a hydrostatic exponential atmosphere with the pressure=1.0 and density=1.0 at the bottom. Assumes constant gravitational acceleration (uniform gravity field).

• GravityEquilibriumTestScaleHeight (external) - The scale height for the exponential atmosphere . Default: 0.1

Collapse Test (27)

A self-gravity test.

• CollapseTestInitialTemperature (external) - Initial gas temperature. Default: 1000 K. Units: degrees Kelvin
• CollapseTestNumberOfSpheres (external) - Number of spheres to collapse; must be <= MAX_SPHERES=10 (see Grid.h for definition). Default: 1
• CollapseTestRefineAtStart (external) - Boolean flag. Type: integer. If TRUE, then initializing routine refines the grid to the desired level. Default: 1 (TRUE)
• CollapseTestSphereCoreRadius (external) - An array of core radii for collapsing spheres. Default: 0.1 (for all spheres)
• CollapseTestSphereDensity (external) - An array of density values for collapsing spheres. Default: 1.0 (for all spheres)
• CollapseTestSpherePosition (external) - A two-dimensional array of coordinates for sphere centers. Type: float[MAX_SPHERES][MAX_DIMENSION]. Default for all spheres: 0.5*(DomainLeftEdge[dim] + DomainRightEdge[dim])
• CollapseTestSphereRadius (external) - An array of radii for collapsing spheres. Default: 1.0 (for all spheres)
• CollapseTestSphereTemperature (external) - An array of temperatures for collapsing spheres. Default: 1.0. Units: degrees Kelvin
• CollapseTestSphereType (external) - An integer array of sphere types. Default: 0
• CollapseTestSphereVelocity (external) - A two-dimensional array of sphere velocities. Type: float[MAX_SPHERES][MAX_DIMENSION]. Default: 0.0
• CollapseTestUniformVelocity (external) - Uniform velocity. Type: float[MAX_DIMENSION]. Default: 0 (for all dimensions)
• CollapseTestUseColour (external) - Boolean flag. Type: integer. Default: 0 (FALSE)
• CollapseTestUseParticles (external) - Boolean flag. Type: integer. Default: 0 (FALSE)

Cosmology Simulation (30)

A sample cosmology simulation.

• CosmologySimulationDensityName (external) - This is the name of the file which contains initial data for baryon density. Type: string. Example: GridDensity. Default: none
• CosmologySimulationTotalEnergyName (external) - This is the name of the file which contains initial data for total energy. Default: none
• CosmologySimulationGasEnergyName (external) - This is the name of the file which contains initial data for gas energy. Default: none
• CosmologySimulationVelocity[123]Name (external) - These are the names of the files which contain initial data for gas velocities. Velocity1 - x-component; Velocity2 - y-component; Velocity3 - z-component. Default: none
• CosmologySimulationParticleMassName (external) - This is the name of the file which contains initial data for particle masses. Default: none
• CosmologySimulationParticlePositionName (external) - This is the name of the file which contains initial data for particle positions. Default: none
• CosmologySimulationParticleVelocityName (external) - This is the name of the file which contains initial data for particle velocities. Default: none
• CosmologySimulationNumberOfInitialGrids (external) - The number of grids at startup. 1 means top grid only. If >1, then nested grids are to be defined by the following parameters. Default: 1
• CosmologySimulationSubgridsAreStatic (external) - Boolean flag, defines whether the subgrids introduced at the startup are static or not. Type: integer. Default: 1 (TRUE)
• CosmologySimulationGridLevel (external) - An array of integers setting the level(s) of nested subgrids. Max dimension MAX_INITIAL_GRIDS is defined in CosmologySimulationInitialize.C as 10. Default for all subgrids: 1, 0 - for the top grid (grid #0)
• CosmologySimulationGridDimension[#] (external) - An array (arrays) of 3 integers setting the dimensions of nested grids. Index starts from 1. Max number of subgrids MAX_INITIAL_GRIDS is defined in CosmologySimulationInitialize.C as 10. Default: none
• CosmologySimulationGridLeftEdge[#] (external) - An array (arrays) of 3 floats setting the left edge(s) of nested subgrids. Index starts from 1. Max number of subgrids MAX_INITIAL_GRIDS is defined in CosmologySimulationInitialize.C as 10. Default: none
• CosmologySimulationGridRightEdge[#] (external) - An array (arrays) of 3 floats setting the right edge(s) of nested subgrids. Index starts from 1. Max number of subgrids MAX_INITIAL_GRIDS is defined in CosmologySimulationInitialize.C as 10. Default: none
• CosmologySimulationUseMetallicityField (external) - Boolean flag. Type: integer. Default: 0 (FALSE)
• CosmologySimulationInitialFractionH2I (external) - The fraction of molecular hydrogen (H_2) at InitialRedshift. This and the following chemistry parameters are used if MultiSpecies is defined as 1 (TRUE). Default: 2.0e-20
• CosmologySimulationInitialFractionH2II (external) - The fraction of singly ionized molecular hydrogen (H2+) at InitialRedshift. Default: 3.0e-14
• CosmologySimulationInitialFractionHeII (external) - The fraction of singly ionized helium at InitialRedshift. Default: 1.0e-14
• CosmologySimulationInitialFractionHeIII (external) - The fraction of doubly ionized helium at InitialRedshift. Default: 1.0e-17
• CosmologySimulationInitialFractionHII (external) - The fraction of ionized hydrogen at InitialRedshift. Default: 1.2e-5
• CosmologySimulationInitialFractionHM (external) - The fraction of negatively charged hydrogen (H-) at InitialRedshift. Default: 2.0e-9
• CosmologySimulationInitialTemperature (external) - A uniform temperature value at InitialRedshift (needed if the initial gas energy field is not supplied). Default: 550*((1.0 + InitialRedshift)/201)²
• CosmologySimulationOmegaBaryonNow (external) - This is the contribution of baryonic matter to the energy density at the current epoch (z=0), relative to the value required to marginally close the universe. Typical value 0.06. Default: 1.0
• CosmologySimulationOmegaCDMNow (external) - This is the contribution of CDM to the energy density at the current epoch (z=0), relative to the value required to marginally close the universe. Typical value 0.94. Default: 0.0 (no dark matter)

Supernova Restart Simulation (40)

All of the supernova parameters are to be put into a restart dump's parameter file. Note that ProblemType must be reset to 40, otherwise these are ignored.

• SupernovaRestartEjectaCenter[#] (external) - Input is a trio of coordinates in code units where the supernova's energy and mass ejecta will be centered. Default: FLOAT_UNDEFINED
• SupernovaRestartEjectaEnergy (external) - The amount of energy instantaneously output in the simulated supernova, in units of 1e51 ergs. Default: 1.0
• SupernovaRestartEjectaMass (external) - The mass of ejecta in the supernova, in units of solar masses. Default: 1.0
• SupernovaRestartEjectaRadius (external) - The radius over which the above two parameters are spread. This is important because if it's too small the timesteps basically go to zero and the simulation takes forever, but if it's too big then you loose information. Units are parsecs. Default: 1.0 pc
• SupernovaRestartName (external) - This is the name of the restart data dump that the supernova problem is initializing from.
• SupernovaRestartColourField - Reserved for future use.

Other External Parameters

• huge_number (external) - The largest reasonable number. Rarely used. Default: 1e+20
• tiny_number (external) - A number which is smaller than all physically reasonable numbers. Used to prevent divergences and divide-by-zero in the following C++ functions: ComputeElementalDensity(), ComputePressure(), ComputePressureDualEnergyFormalism(), ComputeTemperatureField(), ComputeTimeStep(), CorrectForRefinedFluxes(). Problem dependent. Modify with caution! Default: 1e-20.

A currently independent analog, tiny, defined in fortran.def, does the same job for a large family of FORTRAN routines: calcdiss(), calc_dt(), calc_rates(), colh2diss(), coll_rates(), cool1d_multi(), cool1d(), cool_multi_time(), cool_time(), euler(), grid_cic(), interp3d(), inteuler(), int_lin3d(), intrmp(), lgrg(), multi_cool(), ppm_de(), ppm_lr(), solve_cool(), solve_rate(), tscint[123]d(), zeus_main(), zeus_source(). Modification of tiny must be done with caution and currently requires recompiling the code, since tiny is not a parameter yet.

• TimeActionParameter[#] - Reserved for future use.
• TimeActionRedshift[#] - Reserved for future use.
• TimeActionTime[#] - Reserved for future use.
• TimeActionType[#] - Reserved for future use.

Other Internal Parameters

• TimeLastRestartDump - Reserved for future use.
• TimeLastDataDump (internal) - The code time at which the last time-based output occurred.
• TimeLastHistoryDump - Reserved for future use.
• TimeLastMovieDump (internal) - The code time at which the last movie dump occurred.
• CycleLastRestartDump - Reserved for future use.
• CycleLastDataDump (internal) - The cycle number at which the last cycle-based output occurred.
• CycleLastHistoryDump - Reserved for future use.
• InitialCPUTime - Reserved for future use.
• InitialCycleNumber (internal) - One cycle is one top grid timestep. This is the cycle number of the current step. Default: 0
• RestartDumpNumber - Reserved for future use.
• DataLabel[#] (internal) - These are printed out into the restart dump parameter file. One Label is produced per baryon field with the name of that baryon field. The same labels are used to name data sets in HDF files.
• DataUnits[#] - Reserved for future use.
• DataDumpNumber (internal) - The identification number of the next output file (the 0000 part of the output name). This is used and incremented by both the cycle based and time based outputs. Default: 0
• HistoryDumpNumber - Reserved for future use.
• MovieDumpNumber (internal) - The identification number of the next movie output file. Default: 0
• VersionNumber (internal) - Sets the version number of the code which is written out to restart dumps.

Parameters to be Described

• PointSourceGravityCoreRadius (external)