# qr_li¶

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

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

Perform a QR decomposition with pivoting, discard columns where R[i,i] < cuttoff, reverse the permututation from pivoting and perform another QR decomposition to ensure that R is upper right.

Parameters

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

Returns

Q, R – Decomposition of A into isometry Q^d Q = 1 and upper right R with diagonal entries larger than cutoff.

Return type

numpy.ndarray