Struct OneFifthRule 

pub struct OneFifthRule {
    pub increase_factor: f64,
    pub decrease_factor: f64,
    pub window_size: usize,
    pub target_success_rate: f64,
    /* private fields */
}

Rechenberg’s 1/5 success rule for step-size adaptation

If the success rate is above 1/5, increase step size (more exploration) If the success rate is below 1/5, decrease step size (more exploitation)

Reference: Rechenberg, I. (1973). Evolutionsstrategie.

Fields

increase_factor: f64

Factor to increase step size (typically 1.22 ≈ e^(1/5))

decrease_factor: f64

Factor to decrease step size (typically 0.82 ≈ e^(-1/5))

window_size: usize

Window size for computing success rate

target_success_rate: f64

Target success rate (default: 0.2)

Implementations

impl OneFifthRule

pub fn new() -> Self

Create a new 1/5 rule adapter with default parameters

pub fn with_factors(self, increase: f64, decrease: f64) -> Self

Set custom factors

pub fn with_window_size(self, size: usize) -> Self

Set window size

pub fn with_target_rate(self, rate: f64) -> Self

Set target success rate

pub fn record(&mut self, success: bool)

Record a mutation outcome

pub fn success_rate(&self) -> Option<f64>

Get current success rate

pub fn adapt(&self, sigma: f64) -> f64

Adapt a step size based on current success rate

pub fn reset(&mut self)

Reset the history

Trait Implementations

impl Clone for OneFifthRule

fn clone(&self) -> OneFifthRule

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for OneFifthRule

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

Formats the value using the given formatter.

impl Default for OneFifthRule

fn default() -> Self

Returns the “default value” for a type.