Enum Probabilities 

pub enum Probabilities {
    Dense(Vec<f64>),
    Factored {
        blocks: Vec<FactoredBlock>,
        total_qubits: usize,
    },
}

Probability distribution over computational basis states.

For monolithic simulations this wraps a dense Vec<f64> of length 2^n. For decomposed simulations with independent subsystems, this stores per-block marginal distributions that are multiplied on demand, avoiding the O(2^N) Kronecker product unless explicitly requested.

Variants

Dense(Vec<f64>)

Full probability vector of length 2^n.

Factored

Lazy Kronecker product of independent block distributions.

Fields

blocks: Vec<FactoredBlock>

Per-block marginal probability vectors and bitmasks.

total_qubits: usize

Total qubit count across all blocks.

Implementations

impl Probabilities

pub fn len(&self) -> usize

Number of basis states (2^n).

pub fn is_empty(&self) -> bool

Always false, a probability distribution has at least one state.

pub fn get(&self, index: usize) -> f64

Probability of a single computational basis state. O(1) for dense, O(K) for factored where K is the number of independent blocks.

Panics

Panics if index >= self.len().

pub fn iter(&self) -> ProbabilitiesIter<'_>

Iterate over all basis-state probabilities in order.

For Dense this is a direct slice iteration. For Factored each probability is computed on the fly in O(K) per element.

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

Materialize the full probability vector. O(1) clone for dense, O(K x 2^N) for factored. Prefer Probabilities::get for spot-checking.

Trait Implementations

impl Clone for Probabilities

fn clone(&self) -> Probabilities

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Probabilities

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

Formats the value using the given formatter.

impl Index<usize> for Probabilities

fn index(&self, index: usize) -> &f64

Index into a dense probability vector.

Only works for Dense. Panics on Factored because Index must return &f64 and factored values are computed, not stored. Use Probabilities::get or Probabilities::iter instead.

type Output = f64

The returned type after indexing.