TuckerTensorTrain.squash_tails

t3toolbox.tucker_tensor_train.TuckerTensorTrain.squash_tails()

def squash_tails(
        self,
) -> 'TuckerTensorTrain':

Make leading and trailing TT ranks equal to 1 (r0=rd=1), without changing represented dense tensor.

Returns:

• TuckerTensorTrain – Tucker tensor train with tt_ranks=(1,r1,...,r(d-1),1).

• See Also

• ———

• TuckerTensorTrain.tt_ranks

Return type:

TuckerTensorTrain

Examples

>>> import numpy as np
>>> import t3toolbox.tucker_tensor_train as t3
>>> np.random.seed(0)
>>> randn = np.random.randn
>>> tucker_cores = (randn(2,3, 4,10), randn(2,3, 5,11), randn(2,3, 6,12))
>>> tt_cores = (randn(2,3, 2,4,3), randn(2,3, 3,5,2), randn(2,3, 2,6,5))
>>> x = t3.TuckerTensorTrain(tucker_cores, tt_cores)
>>> print(x.tt_ranks)
(2, 3, 2, 5)
>>> x2 = x.squash_tails()
>>> print(x2.tt_ranks)                  # leading/trailing bonds forced to 1
(1, 3, 2, 1)
>>> print(np.allclose(x.to_dense(), x2.to_dense()))   # same dense tensor
True