UT3FrameWeights.from_ut3weights

classmethod t3toolbox.uniform_frame_variations_format.UT3FrameWeights.from_ut3weights(weights)

def from_ut3weights(cls, weights: 'ut3.UT3Weights') -> 'UT3FrameWeights':

Build a tangent metric from uniform base-point edge weights (e.g. UT3Weights.from_ut3svd(x)): up = down = tucker, left = tt[:-1], right = tt[1:], on the supercores and the masks. The TT slicing follows the H_i bond convention (H_i’s left bond is TT bond i, its right bond is bond i+1) – simple but convention-dependent, hence a named method.

The result pairs with a minimal-rank tangent (where the complement rank nD equals the Tucker rank nU, as for ut3svd output); a non-minimal tangent has nD < nU and is rejected by is_consistent_with() rather than silently absorbed. The Grasedyck-Kramer metric is UT3FrameWeights.from_ut3weights(UT3Weights.from_ut3svd(x)).reciprocal().

Parameters:

weights (UT3Weights)

Return type:

UT3FrameWeights