T3Weights.has_shared_tucker_weights
===================================

.. py:method:: t3toolbox.tucker_tensor_train.T3Weights.has_shared_tucker_weights(sharing, rtol = 1e-09)

   .. code-block:: python

      def has_shared_tucker_weights(
              self,
              sharing:    typ.Sequence,   # len=d; one hashable group label per mode
              rtol:       float = 1e-9,   # relative tolerance on the Tucker-weight deviation
      ) -> NDArray:  # bool array, shape = stack_shape (scalar/0-d when unstacked)


   True (per stack element) if the Tucker weights are equal within every sharing group --
   i.e. these weights are COMPATIBLE with the sharing partition: absorbing them into a tied
   T3 keeps it tied (Tucker weights scale the factors; equal group weights scale a shared
   factor identically). TT-bond weights are unconstrained (they never touch the factors).

   Non-enforcing checker (see :py:func:`~t3toolbox.backend.sharing.t3_tucker_weights_sharing_residual`):
   absorbing group-unequal weights is legitimate -- it just unties the result. Weights built
   from the grouped T3-SVD (``from_t3svd(x, sharing=...)``) are group-equal by construction,
   and ``reciprocal``/``sqrt``/``concatenate``/``kronecker`` preserve group-equality.

   .. rubric:: Examples

   >>> import numpy as np
   >>> import t3toolbox.tucker_tensor_train as t3
   >>> np.random.seed(0)
   >>> x = t3.TuckerTensorTrain.randn((6, 6, 5), (3, 3, 2), (1, 3, 2, 1))
   >>> tk, tt = x.data
   >>> xs = t3.TuckerTensorTrain((tk[0], tk[0], tk[2]), tt)         # a tied point
   >>> W = t3.T3Weights.from_t3svd(xs, sharing=(0, 0, 1))           # the grouped spectra
   >>> print(bool(W.has_shared_tucker_weights((0, 0, 1))))
   True
   >>> W2 = t3.T3Weights.from_t3svd(xs)                             # per-mode spectra: unequal
   >>> print(bool(W2.has_shared_tucker_weights((0, 0, 1))))
   False
   >>> xa = t3.t3_absorb_weights(xs, W.reciprocal())                # compatible weights ...
   >>> print(bool(np.all(xa.has_shared_tucker_factors((0, 0, 1))))) # ... keep the T3 tied
   True