- if a new basis is entirely encompases within the current basis within
   numerical precision it can consist entirely of zeros. When normalising
   a basis vector of zeros it leads to a basis of NaNs, which gets added
   to the current basis set. This will give NaN values in likelihoods
   calculated using the ROQ.
 - this patch checks if the normalisation is zero and if so will not add
   the new basis to the current basis as it is unnecessary.