wanted to pass as little as possible in memory. I remember you mentioning there was possibly a memory bug with the interpolation code.

In any case, my original intent was to just "append" to the hdf5 file instead of truncating and re-writing, but hdf5 has some issues with regards to creating new groups etc. Will work on making this more elegant though, that way we write the stuff to disk only once. Think it would be nice to store the coordinates anyway, that way we can go back and see what was simulated.