qr_li

  • full name: tenpy.tools.math.qr_li

  • parent module: tenpy.tools.math

  • type: function

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
Anumpy.ndarray

Matrix to be decomposed as A = Q.R

Returns
Q, Rnumpy.ndarray

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