Given a matrix, M, find a matrix N giving a basis for the
null space. That is t(N) %*% M
is the zero and N has the maximum number of linearly
independent columns.
Usage
Null(M)
Arguments
M
Input matrix. A vector is coerced to a 1-column matrix.
Value
The matrix N with the basis for the null space, or an empty
vector if the matrix M is square and of maximal rank.
References
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
# The function is currently defined asfunction(M)
{
tmp <- qr(M)
set <- if(tmp$rank == 0) 1:ncol(M) else - (1:tmp$rank)
qr.Q(tmp, complete = TRUE)[, set, drop = FALSE]
}