Preprint 27/2021

Maximum relative distance between symmetric rank-two and rank-one tensors

Henrik Eisenmann and André Uschmajew

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Submission date: 24. Nov. 2021 (revised version: November 2021)
Pages: 16
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It is shown that the relative distance in Frobenius norm of a real symmetric order-d tensor of rank two to its best rank-one approximation is upper bounded by   -------------- ∘ 1 − (1 − 1∕d)d−1. This is achieved by determining the minimal possible ratio between spectral and Frobenius norm for symmetric tensors of border rank two, which equals (1− 1∕d)(d1)2. These bounds are also verified for nonsymmetric tensors of order d = 3.

26.11.2021, 12:02