How to use error estimators with block operators

[acfisher]

At the workshop someone asked how to do this a small example of setting up a composite error estimator would be a useful HowTo article.

[tangqi]

Not sure if it is an overkill but I had something in my app:
https://github.com/mfem/mfem/blob/tds-mhd-dev/miniapps/mhd/BlockZZEstimator.hpp
This is a simple sum of two ZZ estimators.

[acfisher]

Yeah this is basically what I was thinking. Are you interested in cutting this down to the bare bones of the code and writing a HowTo article on this?

[tangqi]

Sure. I will provide this HowTo in a week or two. I will likely need your suggestion/help while I am working on it.