Paul Price noticed that the use of unsigned (== uint32, usually) as the index type for Eigen matrices in jointcal might be a problem:

• Eigen docs appear to want a signed integer;
• our number of sources in some of our processing is approaching 2^31.

There's no hard evidence that this is what's causing the segfault we're seeing when processing the (larger, still-proprietary) HSC UltraDeep, and since unsigned should be able to handle 2^32, I'm personally skeptical that this is the problem.  But it should be easy to fix, and a good thing to do regardless, especially for the first reason.

std::ptrdiff_t is probably the right choice to use instead - that will be a signed integer as large as the pointer type (i.e. int64, usually), and hence the largest unsigned type that's actually usable as an index.