py21cmfast.inputs.UserParams

class py21cmfast.inputs.UserParams(*args, **kwargs)

Structure containing user parameters (with defaults).

To see default values for each parameter, use UserParams._defaults_. All parameters passed in the constructor are also saved as instance attributes which should be considered read-only. This is true of all input-parameter classes.

Parameters:

• HII_DIM (int, optional) – Number of cells for the low-res box. Default 200.

• DIM (int,optional) – Number of cells for the high-res box (sampling ICs) along a principal axis. To avoid sampling issues, DIM should be at least 3 or 4 times HII_DIM, and an integer multiple. By default, it is set to 3*HII_DIM.

• NON_CUBIC_FACTOR (float, optional) – Factor which allows the creation of non-cubic boxes. It will shorten/lengthen the line of sight dimension of all boxes. NON_CUBIC_FACTOR * DIM/HII_DIM must result in an integer

• BOX_LEN (float, optional) – Length of the box, in Mpc. Default 300 Mpc.

• HMF (int or str, optional) – Determines which halo mass function to be used for the normalisation of the collapsed fraction (default Sheth-Tormen). If string should be one of the following codes: 0: PS (Press-Schechter) 1: ST (Sheth-Tormen) 2: Watson (Watson FOF) 3: Watson-z (Watson FOF-z)

• USE_RELATIVE_VELOCITIES (int, optional) – Flag to decide whether to use relative velocities. If True, POWER_SPECTRUM is automatically set to 5. Default False.

• POWER_SPECTRUM (int or str, optional) – Determines which power spectrum to use, default EH (unless USE_RELATIVE_VELOCITIES is True). If string, use the following codes: 0: EH 1: BBKS 2: EFSTATHIOU 3: PEEBLES 4: WHITE 5: CLASS (single cosmology)

• N_THREADS (int, optional) – Sets the number of processors (threads) to be used for performing 21cmFAST. Default 1.

• PERTURB_ON_HIGH_RES (bool, optional) – Whether to perform the Zel’Dovich or 2LPT perturbation on the low or high resolution grid.

• NO_RNG (bool, optional) – Ability to turn off random number generation for initial conditions. Can be useful for debugging and adding in new features

• USE_FFTW_WISDOM (bool, optional) – Whether or not to use stored FFTW_WISDOMs for improving performance of FFTs

• USE_INTERPOLATION_TABLES (bool, optional) – If True, calculates and evaluates quantites using interpolation tables, which is considerably faster than when performing integrals explicitly.

• FAST_FCOLL_TABLES (bool, optional) – Whether to use fast Fcoll tables, as described in Appendix of Muñoz+21 (2110.13919). Significant speedup for minihaloes.

• USE_2LPT (bool, optional) – Whether to use second-order Lagrangian perturbation theory (2LPT). Set this to True if the density field or the halo positions are extrapolated to low redshifts. The current implementation is very naive and adds a factor ~6 to the memory requirements. Reference: Scoccimarro R., 1998, MNRAS, 299, 1097-1118 Appendix D.

• MINIMIZE_MEMORY (bool, optional) – If set, the code will run in a mode that minimizes memory usage, at the expense of some CPU/disk-IO. Good for large boxes / small computers.

Methods

__init__(*args, **kwargs)
clone(**kwargs)	Make a fresh copy of the instance with arbitrary parameters updated.
convert(key, val)	Make any conversions of values before saving to the instance.
get_fieldnames([cstruct])	Obtain the C-side field names of this struct.
get_fields([cstruct])	Obtain the C-side fields of this struct.
get_pointer_fields([cstruct])	Obtain all pointer fields of the struct (typically simulation boxes).
refresh_cstruct()	Delete the underlying C object, forcing it to be rebuilt.
update(**kwargs)	Update the parameters of an existing class structure.

Attributes

DIM	Number of cells for the high-res box (sampling ICs) along a principal axis.
FAST_FCOLL_TABLES	Check that USE_INTERPOLATION_TABLES is True.
HII_tot_num_pixels	Total number of pixels in the low-res box.
HMF	The HMF to use (an int, mapping to a given form).
NON_CUBIC_FACTOR	Factor to shorten/lengthen the line-of-sight dimension (non-cubic boxes).
POWER_SPECTRUM	The power spectrum generator to use, as an integer.
USE_INTERPOLATION_TABLES	Whether to use interpolation tables for integrals, speeding things up.
defining_dict	Pure python dictionary representation of this class, as it would appear in C.
fieldnames	List names of fields of the underlying C struct.
fields	List of fields of the underlying C struct (a list of tuples of "name, type").
hmf_model	String representation of the HMF model used.
pointer_fields	List of names of fields which have pointer type in the C struct.
power_spectrum_model	String representation of the power spectrum model used.
primitive_fields	List of names of fields which have primitive type in the C struct.
pystruct	A pure-python dictionary representation of the corresponding C structure.
self	Dictionary which if passed to its own constructor will yield an identical copy.
tot_fft_num_pixels	Total number of pixels in the high-res box.