The column permutation, 0-based (R's pivot minus 1).
Compact form: the upper triangle holds R; the part below the diagonal holds the Householder vectors that represent Q.
Auxiliary information about Q: the leading elements of the Householder vectors for the LINPACK method (ncol
elements), tau for the LAPACK method (one per reflection, min(nrow, ncol) elements).
The computed rank of the matrix. Always min(nrow, ncol) for lapack: true.
Whether the decomposition was computed with lapack: true (R's attr(, "useLAPACK")).
A QR decomposition returned by qr, in R's compact form. Pass it to qrQ, qrR, qrCoef and the other
qr*functions.