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libyt Documents

Set yt Parameters

Table of contents

yt_set_Parameters 

int yt_set_Parameters( yt_param_yt *param_yt )
  • Usage: Set yt parameters, number of fields, number of particle types and how many attributes do each of them have, and number of local grids exist on this MPI rank.
  • Notes:
    • We will reset all cosmological parameters (e.g. current_redshift, omega_lambda, omega_matter, hubble_constant) to 0 if cosmological_simulation is 0.
  • Return: YT_SUCCESS or YT_FAIL

yt_param_yt

  • const char* frontend (Default=NULL)
    • Usage: Field information of the yt frontend to borrow from. This should be yt supported frontend.

      :pencil2: Please make sure the lifetime of frontend covers yt_commit if you set check_data to true when initializing libyt.

  • const char* fig_basename (Default="Fig")
    • Usage: Base name of the output figures. Figure name will also be followed by counter number and yt functionality name.
  • double domain_left_edge[3], domain_right_edge[3] (Default=DBL_UNDEFINED)
    • Usage: Simulation left and right edge in code units.
  • double current_time (Default=DBL_UNDEFINED)
    • Usage: Simulation time in code units.
  • double current_redshift (Default=DBL_UNDEFINED)
    • Usage: Redshift.
  • double omega_lambda (Default=DBL_UNDEFINED)
    • Usage: Dark energy mass density.
  • double omega_matter (Default=DBL_UNDEFINED)
    • Usage: Dark matter mass density.
  • double hubble_constant (Default=DBL_UNDEFINED)
    • Usage: Dimensionless Hubble parameter at the present day.
  • double length_unit (Default=DBL_UNDEFINED)
    • Usage: Simulation length unit in cm (CGS).
  • double mass_unit (Default=DBL_UNDEFINED)
    • Usage: Simulation mass unit in g (CGS).
  • double time_unit (Default=DBL_UNDEFINED)
    • Usage: Simulation time unit in s (CGS).
  • double magnetic_unit (Default=1.0)
    • Usage: Simulation magnetic unit in gauss.
  • int periodicity[3] (Default=INT_UNDEFINED)
    • Usage: Periodicity along each dimension [x][y][z].
    • Valid Value:
      • 0: No
      • 1: Yes
  • int cosmological_simulation (Default=INT_UNDEFINED)
    • Usage: Cosmological simulation dataset.
    • Valid Value:
      • 0: No
      • 1: Yes
  • int dimensionality (Default=INT_UNDEFINED)
    • Usage: Dimensionality of the simulation.

      :warning: We only support 3 for now.

  • int domain_dimensions[3] (Default=INT_UNDEFINED)
    • Usage: Number of cells along each dimension on the root AMR level.
  • int refine_by (Default=INT_UNDEFINED)
    • Usage: Refinement factor between a grid and its subgrid.
  • int index_offset (Default=0)
    • Usage: Index offset.
  • long num_grids (Default=LNG_UNDEFINED)
    • Usage: Total number of grids.
  • int num_grids_local (Default=0)
    • Usage: Number of local grids store on this rank now.
  • int num_fields (Default=0)
    • Usage: Number of fields.
  • int num_par_types (Default=0)
    • Usage: Number of particle types.
  • yt_par_type* par_type_list (Default=NULL)
    • Usage: Particle type list. This should be a yt_par_type array.
    • Data member in yt_par_type:
      • const char* par_type: Name of the particle type.

        :pencil2: Please make sure the lifetime of par_type covers the whole in situ process in libyt. libyt only borrows this name and does not make a copy.

      • int num_attr: Number of attributes this particle type has.

Example 

yt_param_yt param_yt;
param_yt.frontend = "gamer";                          // simulation frontend that libyt borrows field info from
param_yt.fig_basename = "FigName";                    // figure base name (default=Fig)
param_yt.length_unit = 3.0857e21;                     // length unit (cm)
param_yt.mass_unit = 1.9885e33;                       // mass unit (g)
param_yt.time_unit = 3.1557e13;                       // time unit (sec)
param_yt.current_time = time;                         // simulation time in code units
param_yt.dimensionality = 3;                          // dimensionality, support 3 only
param_yt.refine_by = REFINE_BY;                       // refinement factor between a grid and its subgrid
param_yt.num_grids = num_grids;                       // number of grids
param_yt.num_grids_local = num_grids_local;           // number of local grids
param_yt.num_fields = num_fields + 1;                 // number of fields, addition one for derived field demo
param_yt.num_par_types = num_par_types;               // number of particle types

yt_par_type par_type_list[num_par_types];
par_type_list[0].par_type = "io";
par_type_list[0].num_attr = 4;
param_yt.par_type_list = par_type_list;               // define name and number of attributes in each particle

for (int d = 0; d < 3; d++) {
    param_yt.domain_dimensions[d] = NGRID_1D * GRID_DIM; // domain dimensions in [x][y][z]
    param_yt.domain_left_edge[d] = 0.0;                  // domain left edge in [x][y][z]
    param_yt.domain_right_edge[d] = box_size;            // domain right edge in [x][y][z]
    param_yt.periodicity[d] = 0;                         // periodicity in [x][y][z]
}

param_yt.cosmological_simulation = 0;                 // if this is a cosmological simulation or not, 0 for false
param_yt.current_redshift = 0.5;                      // current redshift
param_yt.omega_lambda = 0.7;                          // omega lambda
param_yt.omega_matter = 0.3;                          // omega matter
param_yt.hubble_constant = 0.7;                       // hubble constant

if (yt_set_Parameters(&param_yt) != YT_SUCCESS) {
    fprintf(stderr, "ERROR: yt_set_Parameters() failed!\n");
    exit(EXIT_FAILURE);
}