Requirements

The following libraries are required to compile HBT-HERONS.

C++ compiler with OpenMP support.
CMake (version 3.12 or higher)
HDF5
MPI

Compiling

The latest version is available in the official repository. To get a local copy of the master branch, run:

git clone https://github.com/SWIFTSIM/HBT-HERONS.git && cd HBT-HERONS

As HBT-HERONS saves the commit hash and whether the code has been modified (see version tracking) before compiling, it is recommended to compile it from its own separate build folder. This prevents git from identifying changes to the files it tracks.

mkdir build && cd build

The relevant libraries used to compile the code are found through CMake. Then it is a simple case of compiling to generate the HBT executable:

cmake ../ && make -j 4

Note that there are several important compile-time options that can be specified using CMake. Compiling without specifying their values, as we have just done, uses their default values.

Compile-time options

We only show the subset of options that are directly relevant to how a simulation is analysed.

Tip

Using ccmake instead of cmake opens an interactive terminal view showing the all the relevant compile-time options and allows the user to change their value more easily. If you are doing this for the first time, the cache will be empty. You need to press c (configure) to display the options. After you enable/disable the options relevant to your setup, press c again and then g (generate).

Type of simulation

Options relating to whether the simulation is hydrodynamical, and whether to include the thermal energy of gas during subhalo unbinding.

Property	Default	Description
`HBT_DM_ONLY`	`Off`	Enable if the simulation is dark matter only.
`HBT_UNBIND_WITH_THERMAL_ENERGY`	`Off`	Enable to include thermal energy of gas when calculating its binding energy. If enabled, the dataset needs to be loaded from the particle outputs.

Internal precision

These options are used to determine the internal data types used by HBT-HERONS. If you would like to reduce the memory footprint of the code, you can do so using these flags.

Property	Default	Description
`HBT_INT8`	`On`	Represent integers using 8 (`On`) or 4 (`Off`) bytes.
`HBT_REAL8`	`Off`	Represent floats using 8 (`On`) or 4 (`Off`) bytes.
`HBT_REAL4_VEL`	`Off`	Make the code use 4 bytes for velocities, superseeding the choice made in `HBT_REAL8` if `On`. If `Off`, velocities are represented using the same precision specified by `HBT_REAL8`.
`HBT_REAL4_MASS`	`Off`	Make the code use 4 bytes for masses, superseeding the choice made in `HBT_REAL8` if `On`. If `Off`, masses are represented using the same precision specified by `HBT_REAL8`.
`HBT_INPUT_INT8`	`Off`	Represent particle IDs using 8 (`On`) or 4 (`Off`) bytes. DEPRECATED: the code always uses the value specified by `HBT_INT8`.

Miscellaneous

Options relating to parallelism and whether to compute the eigenvalues of the inertia tensors of each subhalo. Recommended to leave as is.

Property	Default	Description
`HBT_USE_OPENMP`	`On`	Whether to enable OMP parallelism within the main code.

Debugging and testing

Options specifiying parallelism within the unit tests, as well as sanity checks throughout the main code.

Property	Default	Description
`HBT_TEST_MPI_NPROCS`	`4`	How many MPI ranks to use within the unit tests.
`HBT_TEST_OMP_NUM_THREADS`	`4`	How many OMP threads to use within the unit tests.
`HBT_CHECK_TRACER_INDEX`	`Off`	Explictly do a sanity check to see if the Subhalo.TracerIndex points to the correct particle, which is checked by comparing the number of particles. Important to enable when testing changes that modify the vector of subhalo particles at some point, since the ordering of particles can change and hence TracerIndex be incorrect.
`HBT_MEASURE_UNBINDING_TIME`	`Off`	Measure and save for each subhalo the timestamps when key steps in the unbinding started and ended. It also saves how many unbinding iterations had to be done, and which MPI rank analysed it. Saved as subhalo properties within the catalogues.