Struct Normal 

pub struct Normal { /* private fields */ }

A continuous distribution characterized by its mean, mu, and standard deviation, sigma.

Mathematical Properties:

• Support: (-∞, +∞)
• PDF: f(x) = (1/(σ√(2π))) × exp(-0.5 × ((x-μ)/σ)²)
• Mean: μ
• Variance: σ²
• 68-95-99.7 rule: ~68% within 1σ, ~95% within 2σ, ~99.7% within 3σ

Example:

// Standard normal (mean=0, std=1)
let standard = sample(addr!("z"), Normal::new(0.0, 1.0).unwrap());

// Parameter with prior
let theta = sample(addr!("theta"), Normal::new(0.0, 2.0).unwrap());

// Likelihood with observation
let likelihood = observe(addr!("y"), Normal::new(1.5, 0.5).unwrap(), 2.0);

// Measurement error model
let true_value = sample(addr!("true_val"), Normal::new(100.0, 10.0).unwrap());
let measurement = true_value.bind(|val| {
    observe(addr!("measured"), Normal::new(val, 2.0).unwrap(), 98.5)
});

Implementations

impl Normal

pub fn new(mu: f64, sigma: f64) -> FugueResult<Self>

Create a new Normal distribution with validated parameters.

pub fn standard() -> Self

Create the standard normal distribution N(0, 1).

FG-29: infallible constructor for the statically-valid mu = 0, sigma = 1 case, so common code does not need new(...).unwrap().

let z = Normal::standard();
assert_eq!(z.mu(), 0.0);
assert_eq!(z.sigma(), 1.0);

pub fn mu(&self) -> f64

Get the mean of the distribution.

pub fn sigma(&self) -> f64

Get the standard deviation of the distribution.

Trait Implementations

impl Clone for Normal

fn clone(&self) -> Normal

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Normal

impl Debug for Normal

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

Formats the value using the given formatter.

impl Distribution<f64> for Normal

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 Normal

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