M is projected on the
orthogonal complement to the matrix (1,t). Orthogonality
is defined w.r.t. an inner product defined by the weights weight.
detrend( M, t, weight = rep(1, nrow(M)) )nrow(M) x
and y as sum(x*w*y).
A numerical vector of length nrow(M), defaults to a vector of
1s.(1,t).
projection.ip