tpl_ca_stochastic_rules.H File Reference

Reproducible stochastic CA rules (Phase 8). More...

#include <cmath>
#include <cstddef>
#include <cstdint>
#include <random>
#include <type_traits>
#include <ah-errors.H>
#include <ca-rng.H>
#include <ca-traits.H>

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Classes
class	Aleph::CA::Forest_Fire_Rule< Engine >
	Forest-fire rule (Drossel & Schwabl, 1992). More...
class	Aleph::CA::SIR_Rule< Engine >
	SIR epidemic transition rule. More...
class	Aleph::CA::Ising_Glauber_Rule< Engine >
	Ising rule with Glauber single-spin-flip dynamics. More...
class	Aleph::CA::Ising_Metropolis_Rule< Engine >
	Ising rule with Metropolis–Hastings single-spin-flip dynamics. More...
class	Aleph::CA::Schelling_Rule< Engine >
	Local approximation of the Schelling segregation model. More...

Namespaces
namespace	Aleph
	Main namespace for Aleph-w library functions.
namespace	Aleph::CA
namespace	Aleph::CA::ca_ising_detail

Enumerations
enum class	Aleph::CA::Forest_Cell : std::uint8_t { Aleph::CA::EMPTY = 0 , Aleph::CA::TREE = 1 , Aleph::CA::BURNING = 2 }
	Discrete states of the forest-fire automaton. More...
enum class	Aleph::CA::SIR_Cell : std::uint8_t { Aleph::CA::S = 0 , Aleph::CA::I = 1 , Aleph::CA::R = 2 }
	Discrete states of the SIR automaton. More...
enum class	Aleph::CA::Schelling_Cell : std::uint8_t { Aleph::CA::EMPTY = 0 , Aleph::CA::TYPE_A = 1 , Aleph::CA::TYPE_B = 2 }
	Discrete states of the Schelling automaton. More...

Functions
template<typename State >
int	Aleph::CA::ca_ising_detail::state_to_spin (const State &v) noexcept
	Map any integral state to a spin in {-1, +1}.
template<typename State >
State	Aleph::CA::ca_ising_detail::spin_to_state (int spin) noexcept
	Inverse of state_to_spin.
template<typename State >
double	Aleph::CA::ca_ising_detail::delta_energy (const State &current, Neighbor_View< State > neighbours, double J, double H)
	Compute the local energy delta for flipping the centre spin.

Detailed Description

Reproducible stochastic CA rules (Phase 8).

Implements four canonical stochastic transition rules on top of the Phase 8 RNG framework (ca-rng.H):

• Forest_Fire_Rule(p_growth, p_lightning) Drossel–Schwabl forest fire automaton.
• SIR_Rule(beta, gamma) Discrete-time SIR epidemic on a lattice.
• Ising_Glauber_Rule(temperature, J, H) / Ising_Metropolis_Rule(temperature, J, H) Single-spin-flip dynamics with two flip-acceptance strategies.
• Schelling_Rule(threshold, p_move, p_fill) Local approximation of Schelling segregation.

Every rule satisfies ContextualRuleLike<R, L> and therefore plugs directly into Synchronous_Engine, Parallel_Synchronous_Engine and Graph_Synchronous_Engine via apply_rule().

Determinism contract: for any rule listed above, given the same initial frame, the same master_seed, the same configuration and the same number of steps, the resulting frame is bit-for-bit identical regardless of the number of worker threads or the partitioning strategy used by the engine. This is achieved by seeding a fresh Engine per (master_seed, step, coord) triple via cell_seed().

Author

Leandro Rabindranath Leon

Definition in file tpl_ca_stochastic_rules.H.