Struct SiteTensorTrain 

pub struct SiteTensorTrain<T: TTScalar> { /* private fields */ }

Site Tensor Train with center canonical form

A tensor train where:

• Tensors at indices < center are left-orthogonal
• Tensors at indices > center are right-orthogonal
• The tensor at the center index is the “center” tensor

Examples

use tensor4all_simplett::{TensorTrain, AbstractTensorTrain, SiteTensorTrain};

// Build a constant tensor train and convert to center-canonical form.
let tt = TensorTrain::<f64>::constant(&[2, 3, 4], 1.0);
let stt = SiteTensorTrain::from_tensor_train(&tt, 1).unwrap();

// The center is at site 1.
assert_eq!(stt.center(), 1);
assert_eq!(stt.len(), 3);

// Converting back preserves tensor train values.
let tt2 = stt.to_tensor_train();
let val = tt2.evaluate(&[0, 1, 2]).unwrap();
assert!((val - 1.0).abs() < 1e-12);

Implementations

impl<T: TTScalar + Scalar + Default> SiteTensorTrain<T>

pub fn new(tensors: Vec<Tensor3<T>>, center: usize) -> Result<Self>

Create a new SiteTensorTrain from tensors with specified center

pub fn from_tensor_train(tt: &TensorTrain<T>, center: usize) -> Result<Self>

Create from TensorTrain with specified center

pub fn center(&self) -> usize

Get the center index

pub fn partition(&self) -> &Range<usize>

Get the partition range

pub fn site_tensors_mut(&mut self) -> &mut [Tensor3<T>]

Get mutable access to site tensors

pub fn move_center_right(&mut self) -> Result<()>

Move the center one position to the right

pub fn move_center_left(&mut self) -> Result<()>

Move the center one position to the left

pub fn set_center(&mut self, new_center: usize) -> Result<()>

Move the center to a specific position

pub fn to_tensor_train(&self) -> TensorTrain<T>

Convert to a regular TensorTrain

pub fn set_site_tensor(&mut self, i: usize, tensor: Tensor3<T>)

Set the tensor at a specific site

Note: This may invalidate the canonical form. Use with caution.

pub fn set_two_site_tensors( &mut self, i: usize, tensor1: Tensor3<T>, tensor2: Tensor3<T>, ) -> Result<()>

Set two adjacent site tensors (useful for TEBD-like algorithms)

Trait Implementations

impl<T: TTScalar + Scalar + Default> AbstractTensorTrain<T> for SiteTensorTrain<T>

fn len(&self) -> usize

Number of sites (core tensors) in the tensor train.

fn site_tensor(&self, i: usize) -> &Tensor3<T>

Borrow the rank-3 core tensor at site i.

fn site_tensors(&self) -> &[Tensor3<T>]

Borrow all core tensors as a slice.

fn is_empty(&self) -> bool

Returns true if the tensor train has zero sites.

fn link_dims(&self) -> Vec<usize>

Bond dimensions at every link (length = len() - 1).

fn link_dim(&self, i: usize) -> usize

Bond dimension at the link between site i and site i+1.

fn site_dims(&self) -> Vec<usize>

Physical (site) dimensions for every site.

fn site_dim(&self, i: usize) -> usize

Physical (site) dimension at site i.

fn rank(&self) -> usize

Maximum bond dimension across all links.

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

Evaluate the tensor train at a given index set

fn sum(&self) -> T

Sum over all indices of the tensor train

fn norm2(&self) -> f64

Squared Frobenius norm: sum_i |T[i]|^2.

fn norm(&self) -> f64

Frobenius norm: sqrt(sum_i |T[i]|^2).

fn log_norm(&self) -> f64

Logarithm of the Frobenius norm: ln(norm()).

impl<T: Clone + TTScalar> Clone for SiteTensorTrain<T>

fn clone(&self) -> SiteTensorTrain<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug + TTScalar> Debug for SiteTensorTrain<T>

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

Formats the value using the given formatter.