Fair enough. But having worked with Fortran code that was designed in pen on yellow legal pads, typed in, and run on a suite of standard test problems chosen t

Fair enough. But having worked with Fortran code that was designed in pen on yellow legal pads, typed in, and run on a suite of standard test problems chosen to expose subtle bugs, I have learned to respect an archaic engineering style of which few people are capable nowadays. Sometimes code is essentially "finished;" you'd be amazed at how rarely it has bugs. It should be changed only with care and for good reasons, not because the programming language changed to conform to some new fad. (FWIW, I'd probably write most new numerical code in Julia rather than Fortran 20xx, and either call into existing Fortran via FFI, or drive it from the command line with some scripting language.)