Struct Exponential 

pub struct Exponential { /* private fields */ }

A continuous distribution often used to model waiting times between events.

Characterized by the memoryless property.

Mathematical Properties:

• Support: [0, +∞)
• PDF: f(x) = λ × exp(-λx) for x ≥ 0
• Mean: 1 / λ
• Variance: 1 / λ²
• Memoryless: P(X > s + t | X > s) = P(X > t)

Example:

// Average wait time of 2 minutes (rate = 0.5 per minute)
let wait_time = sample(addr!("wait"), Exponential::new(0.5).unwrap());

// Service time model
let service = sample(addr!("service_time"), Exponential::new(1.5).unwrap())
    .bind(|time| {
        if time > 5.0 {
            pure("slow")
        } else {
            pure("fast")
        }
    });

// Observe actual waiting time
let observed = observe(addr!("actual_wait"), Exponential::new(0.3).unwrap(), 4.2);

Implementations

impl Exponential

pub fn new(rate: f64) -> FugueResult<Self>

Create a new Exponential distribution with validated parameters.

pub fn rate(&self) -> f64

Get the rate parameter.

Trait Implementations

impl Clone for Exponential

fn clone(&self) -> Exponential

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Exponential

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

Formats the value using the given formatter.

impl Distribution<f64> for Exponential

fn sample(&self, rng: &mut dyn RngCore) -> f64

Generate a random sample (with its natural type), T, from the distribution, using the provided random number generator, rng.

fn log_prob(&self, x: &f64) -> LogF64

Compute the log-probability density (continuous) or mass (discrete) of a value, x, from the distribution.

fn clone_box(&self) -> Box<dyn Distribution<f64>>

Clone the distribution into a boxed trait object, Box<dyn Distribution<T>>.

impl Validate for Exponential

fn validate(&self) -> FugueResult<()>

impl Copy for Exponential