Comment (by User e6f22):

Looking at the pull request and based on discussion in today’s ET call, I have the following review comments:

• since now the if and else branches of the 2nd derivatives are indentical, I would remove the if statement and replace it by a comment. Usually I would suggest replacing it by a check that the passed option is either “minimal bandwidth” or “optimal” choice for the operators, however the current code already does “minimal bandwith” or “other” so there seems little point of adding such a check now.
• I would advocate removing the now dead code from the repository, anyone who needs it can get it back from the version control system
• I would check that the documentation is updated if it mentioned the existence of an “optimal” 2nd derivative operators

Fine to apply otherwise.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2368/instabilities-with-summation-by-parts