Efficiently iterating over Nd array in oct file

[Jordi Gutiérrez Hermoso]

I'm agonising over an implementation detail of bwlabeln. I need to
iterate over each voxel of boolNDArray *and* consider each voxel's
neighbours. If I use a linear index and just iterate up to
boolNDArray::nelem(), I would have to call ind2sub for each pixel in
order to consider its neighbours, and I'm trying to avoid that call. I
was hoping for something like Array<idx_vector>::next() if such a
function existed or to impement it myself. Any other suggestions?

Thanks,
- Jordi G. H.