> This is possibly of wider relevance, but given Gary's insightful comments on the phone today do we also need to include a kInterp option here, not least for our upcoming tests?
> 
I hadn't originally included it on the basis of what he said in his document (and on the phone) that he was quite comfortable with the quintic as the k-space interpolant along with padding by 4x.  However, you are right that if we want to redo those tests in the context of irregular galaxy morphologies, then we need to include that as a keyword.  I could do that here, in order to get it onto master soon.  Would want to be very clear in the documentation that this choice should not be changed willy-nilly, with references to all his careful tests (and in contrast to xInterp which, as he said, is more of a choice).