cdt::Random Class Reference

A run-owned PCG engine with a recorded seed and stream identifier. More...

#include <Random.hpp>

Collaboration diagram for cdt::Random:

Public Types
using	result_type = pcg64::result_type

Public Member Functions
	Random ()
	Construct a root stream from operating-system entropy.
	Random (Random_seed const seed, Random_stream const stream=0)
	Construct a reproducible PCG stream without consulting entropy.
auto	operator() () -> result_type
auto	seed () const noexcept -> Random_seed
auto	split (Random_stream const stream) const -> Random
	Create a fresh reproducible stream from the same root seed.
auto	stream () const noexcept -> Random_stream

Static Public Member Functions
static auto constexpr	max () noexcept -> result_type
static auto constexpr	min () noexcept -> result_type

Static Private Member Functions
static auto	entropy_seed () -> Random_seed

Private Attributes
pcg64	m_engine
Random_seed	m_seed {}
Random_stream	m_stream {}

Detailed Description

A run-owned PCG engine with a recorded seed and stream identifier.

Construct one root engine per simulation. Pass engines by reference to distributions and stochastic algorithms instead of drawing fresh entropy for each sample. split() creates a reproducible, independently parameterized PCG stream for a subsystem or worker.

Random is intentionally not internally synchronized. A mutable instance belongs to one run or one thread. Parallel code must give each worker a distinct stream before drawing from it.

See also

PCG random-number generatorsPCG random-number generators

Definition at line 42 of file Random.hpp.

Member Typedef Documentation

result_type

using cdt::Random::result_type = pcg64::result_type

Definition at line 45 of file Random.hpp.

Constructor & Destructor Documentation

Random() [1/2]

cdt::Random::Random ( )

inline

Construct a root stream from operating-system entropy.

Definition at line 63 of file Random.hpp.

References Random().

Referenced by Random(), and split().

Random() [2/2]

cdt::Random::Random ( Random_seed const seed, Random_stream const stream = 0 )

inlineexplicit

Construct a reproducible PCG stream without consulting entropy.

Parameters

seed	Root seed recorded for the run.
stream	PCG stream selector; distinct values select distinct sequences for the same root seed.

Definition at line 69 of file Random.hpp.

References seed(), and stream().

Member Function Documentation

entropy_seed()

auto cdt::Random::entropy_seed ( ) -> Random_seed

inlinestaticnodiscardprivate

Definition at line 52 of file Random.hpp.

max()

auto constexpr cdt::Random::max ( ) -> result_type

inlinestaticnodiscardconstexprnoexcept

Definition at line 76 of file Random.hpp.

min()

auto constexpr cdt::Random::min ( ) -> result_type

inlinestaticnodiscardconstexprnoexcept

Definition at line 73 of file Random.hpp.

operator()()

auto cdt::Random::operator() ( ) -> result_type

inlinenodiscard

Definition at line 79 of file Random.hpp.

seed()

auto cdt::Random::seed ( ) const -> Random_seed

inlinenodiscardnoexcept

Returns

The effective root seed for replaying this run.

Definition at line 82 of file Random.hpp.

Referenced by Random().

split()

auto cdt::Random::split ( Random_stream const stream ) const -> Random

inlinenodiscard

Create a fresh reproducible stream from the same root seed.

Definition at line 89 of file Random.hpp.

References Random(), and stream().

Referenced by main().

stream()

auto cdt::Random::stream ( ) const -> Random_stream

inlinenodiscardnoexcept

Returns

The PCG stream selector used by this engine.

Definition at line 85 of file Random.hpp.

Referenced by Random(), and split().

Member Data Documentation

m_engine

pcg64 cdt::Random::m_engine

private

Definition at line 50 of file Random.hpp.

m_seed

Random_seed cdt::Random::m_seed {}

private

Definition at line 48 of file Random.hpp.

m_stream

Random_stream cdt::Random::m_stream {}

private

Definition at line 49 of file Random.hpp.

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The documentation for this class was generated from the following file:

• include/Random.hpp