t3_rank_adjustment_sweep

t3toolbox.backend.t3_svd.t3_rank_adjustment_sweep(x, direction='right_to_left')

def t3_rank_adjustment_sweep(
        x: typ.Tuple[
            typ.Tuple[NDArray, ...],  # tucker_cores
            typ.Tuple[NDArray, ...],  # tt_cores
        ],
        direction: str = 'right_to_left',  # 'right_to_left' | 'left_to_right'
) -> typ.Tuple[
    typ.Tuple[NDArray, ...],  # tucker_cores
    typ.Tuple[NDArray, ...],  # tt_cores
]:

A single lossless directional sweep that drops structurally-redundant ranks (re-SVD each Tucker edge and TT bond with no cap). The represented tensor is unchanged.

'right_to_left' produces a right-orthogonal result; 'left_to_right' a left-orthogonal one. A single sweep reaches the minimal ranks only if the input is already orthogonal in the opposite direction – e.g. a t3svd() result is left-orthogonal, so t3_rank_adjustment_sweep(result, 'right_to_left') minimizes it (verify with has_minimal_ranks). On a general input it is a partial reduction; compose both directions for guaranteed minimal ranks.

Parameters:

• x (t3toolbox.backend.common.typ.Tuple[t3toolbox.backend.common.typ.Tuple[NDArray, Ellipsis], t3toolbox.backend.common.typ.Tuple[NDArray, Ellipsis]])

• direction (str)

Return type:

t3toolbox.backend.common.typ.Tuple[t3toolbox.backend.common.typ.Tuple[NDArray, Ellipsis], t3toolbox.backend.common.typ.Tuple[NDArray, Ellipsis]]