Struct SquareLinsolveUpdater 

pub struct SquareLinsolveUpdater<T, V>
where
    T: TensorLike,
    V: Clone + Hash + Eq + Send + Sync + Debug,
{
    pub projected_operator: Arc<RwLock<ProjectedOperator<T, V>>>,
    pub projected_state: ProjectedState<T, V>,
    pub options: LinsolveOptions,
    /* private fields */
}

SquareLinsolveUpdater: Implements LocalUpdater for the square linsolve algorithm.

At each sweep step:

1. Compute local operator (from ProjectedOperator environments)
2. Compute local RHS (from ProjectedState environments)
3. Solve local linear system using GMRES
4. Factorize the result and update the state

This is the V_in = V_out specialized version. The current solution x is used with a separate reference state (with different bond indices) for stable environment computation.

Fields

projected_operator: Arc<RwLock<ProjectedOperator<T, V>>>

Projected operator (3-chain), wrapped in Arc<RwLock> for GMRES.

projected_state: ProjectedState<T, V>

Projected state for RHS (2-chain)

options: LinsolveOptions

Solver options

Implementations

impl<T, V> SquareLinsolveUpdater<T, V>

where T: TensorLike + 'static, T::Index: IndexLike, <T::Index as IndexLike>::Id: Clone + Hash + Eq + Ord + Debug + Send + Sync + 'static, V: Clone + Hash + Eq + Ord + Send + Sync + Debug + 'static,

pub fn new( operator: TreeTN<T, V>, rhs: TreeTN<T, V>, options: LinsolveOptions, ) -> Self

Create a new SquareLinsolveUpdater.

The reference_state will be initialized lazily on the first before_step call.

pub fn with_index_mappings( operator: TreeTN<T, V>, input_mapping: HashMap<V, IndexMapping<T::Index>>, output_mapping: HashMap<V, IndexMapping<T::Index>>, rhs: TreeTN<T, V>, options: LinsolveOptions, ) -> Self

Create a new SquareLinsolveUpdater with index mappings for correct index handling.

Use this when the MPO uses internal indices (s_in_tmp, s_out_tmp) that differ from the state’s site indices. The mappings define how to translate between them.

The reference_state will be initialized lazily on the first before_step call.

Arguments

• operator - The MPO with internal index IDs
• input_mapping - Mapping from true input indices to MPO’s internal indices
• output_mapping - Mapping from true output indices to MPO’s internal indices
• rhs - The RHS b
• options - Solver options

pub fn verify(&self, state: &TreeTN<T, V>) -> Result<LinsolveVerifyReport<V>>

Verify internal data consistency between operator, RHS, and state.

This function checks that:

1. The operator’s site space structure is compatible with the state
2. The operator’s input indices can match the state’s site indices
3. Environment computation requirements are satisfiable

Returns a detailed report of any inconsistencies found.

Trait Implementations

impl<T, V> LocalUpdater<T, V> for SquareLinsolveUpdater<T, V>

where T: TensorLike + 'static, T::Index: IndexLike, <T::Index as IndexLike>::Id: Clone + Hash + Eq + Ord + Debug + Send + Sync + 'static, V: Clone + Hash + Eq + Ord + Send + Sync + Debug + 'static,

fn before_step( &mut self, step: &LocalUpdateStep<V>, full_treetn_before: &TreeTN<T, V>, ) -> Result<()>

Optional hook called before performing an update step.

fn update( &mut self, subtree: TreeTN<T, V>, step: &LocalUpdateStep<V>, full_treetn: &TreeTN<T, V>, ) -> Result<TreeTN<T, V>>

Update a local subtree.

fn after_step( &mut self, step: &LocalUpdateStep<V>, full_treetn_after: &TreeTN<T, V>, ) -> Result<()>

Optional hook called after an update step has been applied to the full TreeTN.