Enum StrategyParams 

pub enum StrategyParams {
    Isotropic(f64),
    NonIsotropic(Vec<f64>),
    Correlated {
        sigmas: Vec<f64>,
        rotations: Vec<f64>,
    },
}

Strategy parameters that can be evolved alongside the genome

Variants

Isotropic(f64)

Single global step size (σ) - (1, σ)-ES or simple ES

NonIsotropic(Vec<f64>)

Per-gene step sizes (σ₁, …, σₙ) - Non-isotropic mutation

Correlated

Full covariance with rotation angles Contains step sizes (σ₁, …, σₙ) and rotation angles (α₁, …, αₖ) where k = n(n-1)/2

Fields

sigmas: Vec<f64>

rotations: Vec<f64>

Implementations

impl StrategyParams

pub fn isotropic(sigma: f64) -> Self

Create isotropic parameters with given step size

pub fn non_isotropic(sigmas: Vec<f64>) -> Self

Create non-isotropic parameters with given step sizes

pub fn correlated(sigmas: Vec<f64>) -> Self

Create correlated parameters

pub fn dimension(&self) -> usize

Get dimension of the strategy parameters

pub fn mutate<R: Rng>(&mut self, n: usize, min_sigma: f64, rng: &mut R)

Mutate the strategy parameters using the log-normal self-adaptation rule.

Following Beyer & Schwefel (2002) and Eiben & Smith (Introduction to Evolutionary Computing §4.4.2), the uncorrelated-mutation update with n step sizes is

σ_i' = σ_i · exp(τ' · N(0,1) + τ · N_i(0,1))

where N(0,1) is drawn once per individual (shared across all coordinates) and N_i(0,1) is drawn independently per coordinate, with:

• τ' = 1/√(2n) on the shared/global deviate — the smaller coefficient, because its effect is coherent across all n coordinates, and
• τ = 1/√(2√n) on the per-coordinate deviate — the larger coefficient.

For the single-step-size (isotropic) case the standard rule is σ' = σ · exp(τ₀ · N(0,1)) with τ₀ = 1/√n (Schwefel).

min_sigma is a caller-supplied, problem-scaled lower bound on the step size; the effective floor is max(min_sigma, SIGMA_UNDERFLOW_FLOOR).

pub fn get_sigma(&self, gene_idx: usize) -> f64

Get step size for a specific gene (for non-isotropic and correlated)

pub fn sigmas(&self) -> Vec<f64>

Get all step sizes

Trait Implementations

impl Clone for StrategyParams

fn clone(&self) -> StrategyParams

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StrategyParams

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for StrategyParams

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for StrategyParams

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.