Struct Dispersion 

pub struct Dispersion { /* private fields */ }

Dispersion contract used by inferential covariance and reference distributions.

This type lives in gam-problem; re-exported here so model result APIs and existing engine code name the same neutral contract. A validated response-level dispersion phi.

A known/fixed dispersion is finite and strictly positive. An estimated dispersion is finite and non-negative: zero is a meaningful boundary result for an exact fit, but any operation that divides by it must explicitly fail. The distinction prevents a zero estimate from being silently promoted to a tiny positive fixed scale.

Implementations

impl Dispersion

pub const UNIT: Dispersion

Exact unit fixed dispersion for fixed-scale likelihoods.

pub const ZERO_ESTIMATE: Dispersion

Exact boundary estimate produced by a zero-residual fit.

pub fn known(phi: f64) -> Result<Dispersion, DispersionError>

Construct a finite, strictly-positive fixed dispersion.

pub fn estimated(phi: f64) -> Result<Dispersion, DispersionError>

Construct a finite, non-negative estimated dispersion.

pub fn from_reciprocal( value: f64, estimated: bool, ) -> Result<Dispersion, DispersionError>

Construct a dispersion from a finite positive precision/shape.

This checks the division itself; a positive subnormal denominator whose reciprocal overflows is rejected instead of being floored.

pub const fn phi(self) -> f64

pub const fn is_estimated(self) -> bool

pub const fn is_zero_estimate(self) -> bool

Whether this is the exact, validated boundary estimate phi = 0.

pub fn reciprocal(self) -> Result<f64, DispersionError>

Return 1 / phi, rejecting the exact boundary and overflow.

pub fn sqrt(self) -> f64

Return sqrt(phi). Zero is represented exactly.

pub fn rescale_estimate( &mut self, multiplier: f64, ) -> Result<bool, DispersionError>

Rescale an estimated dispersion in place.

Fixed dispersions are left unchanged and return Ok(false). The product is checked before mutation so this operation is atomic on error.

Trait Implementations

impl Clone for Dispersion

fn clone(&self) -> Dispersion

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Dispersion

impl Debug for Dispersion

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Dispersion

fn deserialize<__D>( __deserializer: __D, ) -> Result<Dispersion, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Dispersion

fn eq(&self, other: &Dispersion) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Dispersion

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Dispersion

impl TryFrom<DispersionWire> for Dispersion

type Error = DispersionError

The type returned in the event of a conversion error.

fn try_from( value: DispersionWire, ) -> Result<Dispersion, <Dispersion as TryFrom<DispersionWire>>::Error>

Performs the conversion.