Random Number Generator (xoshiro128++) for deterministic, reproducible search.
This module provides a functional wrapper around PyVRP's RandomNumberGenerator. All operations return a new RNG state, preserving immutability.
Example
rng = ExVrp.RNG.new(42)
{rng, value} = ExVrp.RNG.call(rng)
{rng, float} = ExVrp.RNG.rand(rng)
{rng, int} = ExVrp.RNG.randint(rng, 100)Summary
Functions
Generates the next random unsigned 32-bit integer.
Creates a new RNG from an explicit 4-element state.
Returns the maximum value the RNG can produce (2^32 - 1).
Returns the minimum value the RNG can produce (0).
Creates a new RNG from a seed.
Generates a random float uniformly distributed in [0, 1].
Generates a random integer in the range [0, high).
Returns the internal RNG state as a 4-element list.
Types
@type t() :: reference()
Functions
@spec call(t()) :: {t(), non_neg_integer()}
Generates the next random unsigned 32-bit integer.
Returns {new_rng, value} where value is in the range [min(), max()].
Example
{rng, value} = ExVrp.RNG.call(rng)@spec from_state([non_neg_integer()]) :: {:ok, t()} | {:error, term()}
Creates a new RNG from an explicit 4-element state.
Example
rng = ExVrp.RNG.from_state([1, 2, 3, 4])@spec max() :: non_neg_integer()
Returns the maximum value the RNG can produce (2^32 - 1).
@spec min() :: non_neg_integer()
Returns the minimum value the RNG can produce (0).
@spec new(non_neg_integer()) :: t()
Creates a new RNG from a seed.
Example
rng = ExVrp.RNG.new(42)Generates a random float uniformly distributed in [0, 1].
Returns {new_rng, value}.
Example
{rng, float} = ExVrp.RNG.rand(rng)@spec randint(t(), pos_integer()) :: {t(), non_neg_integer()}
Generates a random integer in the range [0, high).
Returns {new_rng, value}.
Example
{rng, value} = ExVrp.RNG.randint(rng, 100) # value in 0..99@spec state(t()) :: [non_neg_integer()]
Returns the internal RNG state as a 4-element list.
Example
state = ExVrp.RNG.state(rng) # [a, b, c, d]