I wrote a lengthy question last year on SO about matrix multiplication. It was answered well, and it had gotten about 20 upvotes and 3000 views. In January a moderator decided controversially to migrate it to Code Review, despite people thinking it was more appropriate for StackOverflow. Now, just recently, the Code Review moderators have decided that it was off-topic for Code Review and locked it. This caused the answers to be migrated back to StackOverflow, but the question is deleted on SO and I can't undelete it. The upshot is that people can no longer see the useful accepted answer (sigh).
The questions are here:
StackOverflow (with answers, deleted) Why is a naïve C++ matrix multiplication 100 times slower than BLAS?
Code Review (no answers, locked) https://codereview.stackexchange.com/questions/20980/naive-c-matrix-multiplication-100-times-slower-than-blas
Basically, I would like the StackOverflow one undeleted, so people can continue to search for and find Eric Postpischil's very useful answer. I've clicked undelete on the StackOverflow one some time ago and there has been no response. Sigh!