meas_modelfit has some issues with Eigen 3.3.4. I am making this a separate ticket from
DM-14305 in hopes that these can be fixed in a way that is backwards compatible.
The first issue is that this does not compile:
but the solution to that is trivial: swap component._sigmaLLT.matrixL() and _workspace, though Jim Bosch suggested a solution that reduces duplication with nearby code.
A more serious concern is that the following code in TruncatedGaussian.cc TruncatedGaussian::maximize raises an assertion error that a matrix is empty when running tests/test_truncatedGaussian.py:
To fix that problem Jim Bosch suggests returning a vector of all zeros if n == k.