Struct EpState 

pub struct EpState<B: Backend> {
    pub parents: Tensor<B, 2>,
    pub sigmas: Tensor<B, 1>,
    pub parent_fitness: Vec<f32>,
    pub best_genome: Option<Tensor<B, 2>>,
    pub best_fitness: f32,
    pub generation: usize,
}

Generation-to-generation state for EvolutionaryProgramming.

The two-phase ask/tell handshake uses parent_fitness.is_empty() as a sentinel: on the very first Strategy::ask call the initial parents are returned unchanged; on the very first Strategy::tell call parent_fitness is populated and best_genome/best_fitness are initialized. Subsequent ask/tell cycles produce, evaluate, and select from the (μ + μ) pool.

During ask, sigmas is temporarily expanded to length 2μ (parent σ concatenated with offspring σ) so tell can apply q-tournament selection over the combined pool without re-deriving σ values. After tell completes, sigmas is back to length μ.

Fields

parents: Tensor<B, 2>

Current parents, shape (μ, D).

sigmas: Tensor<B, 1>

Per-individual step-size σ, shape (μ,) between generations and (2μ,) transiently inside an ask/tell cycle (parent σ ‖ offspring σ).

parent_fitness: Vec<f32>

Host-side fitness cache for the current parents.

Empty before the first Strategy::tell call; length μ thereafter. The is_empty() check distinguishes the initial evaluation phase from subsequent tournament-selection generations.

best_genome: Option<Tensor<B, 2>>

Best-so-far genome, shape (1, D).

None before the first Strategy::tell call.

best_fitness: f32

Best-so-far fitness across all completed generations.

f32::NEG_INFINITY before the first Strategy::tell call (the worst value under the maximise convention).

generation: usize

Number of completed tell calls (zero-based generation index + 1).

Trait Implementations

impl<B: Clone + Backend> Clone for EpState<B>

fn clone(&self) -> EpState<B>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<B: Debug + Backend> Debug for EpState<B>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.