The if-else cases in lsqr.py were not exhaustive. They become exhaustive by changing ab > aa to ab >= aa.
template<class Distances_>
ExplicitDistances<Distances_>::
ExplicitDistances(const Distances& distances):
size_(distances.size()), distances_((distances.size() * (distances.size() + 1))/2)
{
IndexType i = 0;
for (typename Distances::IndexType a = distances.begin(); a != distances.end(); ++a)
for (typename Distances::IndexType b = a; b != distances.end(); ++b)
{
distances_[i++] = distances(a,b);
}
}
template<class Distances_>
typename ExplicitDistances<Distances_>::DistanceType
ExplicitDistances<Distances_>::
operator()(IndexType a, IndexType b) const
{
if (a > b) std::swap(a,b);
return distances_[a*size_ - ((a*(a-1))/2) + (b-a)];
}
template<class Distances_>
typename ExplicitDistances<Distances_>::DistanceType&
ExplicitDistances<Distances_>::
operator()(IndexType a, IndexType b)
{
if (a > b) std::swap(a,b);
return distances_[a*size_ - ((a*(a-1))/2) + (b-a)];
}