find_actualized_shift_values
computes the values of the shifts their
positions, and the mean values at the tips.
Warning : this function does not check for consistency. Please make sure that the
shifts postions and the mean values are compatible.
find_shift_values(shifts_edges, T_tree_ac, vect_Y, p, ntaxa)
incidence.matrix
.qr.solve
for rectangular linear system solving.