Comment (by Zach Etienne):

Thanks for the insights, Erik. It’s great to know that the core infrastructure correctly handles float. Indeed the problem lies with the many, many physics modules that – in all likelihood – have never been run with float. Most if not all of these could/should have CCTK_REAL replaced with double , as setting CCTK_REAL to float would break them.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2686/rename-cctk_real-double-when-float-is-not