Steven:

int index_of(const multi_array<int, 3>& m, int* iter, int dimension) { int offset = iter - m.origin(); return(offset / m.strides()[dimension] % m.shape()[dimension] + m.index_bases()[dimension]); }

Thanks for the code suggestion. Does this code work for N dimensions? it appears to. I would prefer to keep a tight count of the indices in the iterator itself to ensure that we don't need to do this expensive calculation each time, but this looks like a pretty good starting point and would work similarly for my sequential ublas::matrix iteration as well. -Jesse