Struct Contraction 

pub struct Contraction<T: SVDScalar>
where
    <T as ComplexFloat>::Real: Into<f64>,
{ /* private fields */ }

Contraction of two MPOs with caching

This struct efficiently computes the product of two MPOs by caching left and right environments for reuse.

Implementations

impl<T: SVDScalar> Contraction<T>

where <T as ComplexFloat>::Real: Into<f64>,

pub fn new(mpo_a: MPO<T>, mpo_b: MPO<T>) -> Result<Self>

Create a new Contraction from two MPOs

pub fn with_transform<F>(mpo_a: MPO<T>, mpo_b: MPO<T>, f: F) -> Result<Self>

where F: Fn(T) -> T + Send + Sync + 'static,

Create a new Contraction with a transformation function

pub fn len(&self) -> usize

Get the number of sites

pub fn is_empty(&self) -> bool

Check if empty

pub fn result_site_dims(&self) -> Vec<(usize, usize)>

Get site dimensions for the contracted result

Returns (s1_result, s2_result) at each site where:

• s1_result = s1_a (first physical index of A)
• s2_result = s2_b (second physical index of B)

pub fn clear_cache(&mut self)

Clear all cached environments

pub fn evaluate(&mut self, indices: &[(usize, usize)]) -> Result<T>

Evaluate the contraction at a specific set of indices

indices should be [(i1, j1), (i2, j2), …] where:

• i_k is the index for s1 of MPO A at site k
• j_k is the index for s2 of MPO B at site k

pub fn evaluate_left( &mut self, n: usize, indices: &[(usize, usize)], ) -> Result<Matrix2<T>>

Evaluate the left environment up to site n (exclusive)

Returns L[n] = product of sites 0..n

pub fn evaluate_right( &mut self, n: usize, indices: &[(usize, usize)], ) -> Result<Matrix2<T>>

Evaluate the right environment from site n (exclusive) to the end

Returns R[n] = product of sites n..L