# rq_li¶

tenpy.tools.math.rq_li(A, cutoff=1e-15)[source]

RQ decomposition with cutoff to discard nearly linear dependent columns in Q.

Uses qr_li() on tranpose of A. Note that R is nonzero in the lowest left corner; R has entries below the diagonal for non-square R.

Parameters

A (numpy.ndarray) – Matrix to be decomposed as A = Q.R

Returns

R, Q – Decomposition of A into isometry Q Q^d = 1 and upper right R with diagonal entries larger than cutoff. If M, N = A.shape, then R.shape = M, K and Q.shape = K, N with K <= min(M, N).

Return type

numpy.ndarray