Using module variables as dimensions in function arguments

[PierU]

@FortranFan

that can really enable thread-safe computations unlike the read-write approach to some global data (your comments based on feedback from other readers here here re: nx being a MODULE entity).

The point is that if no threading or concurent access is needed at this level, the solution with module variables is valid and reasonnable. I would write things differently if threading/concurrent access was needed.

Sometimes, KISS is good.