a character string. For method = "qr" the rank is computed as
qr(x)\$rank, or alternatively for method = "chol" the
rank is computed as attr(chol(x, pivot = TRUE), "rank").
Details
The function rk computes the rank of a matrix which is the
dimension of the range of the matrix corresponding to the number of
linearly independent rows or columns of the matrix, or to the number
of nonzero singular values.
The rank of a matrix is also named linear map.
References
Golub, van Loan, (1996);
Matrix Computations,
3rd edition. Johns Hopkins University Press.