[Info-vax] [OT] Current students apparently can't read Fortran code...

[Arne Vajhøj]

On 4/13/2022 10:02 PM, Don Baccus wrote:
> On Wednesday, April 13, 2022 at 6:49:05 PM UTC-7, Galen wrote:
>>> Fortran 66 was available for most of that period.
>>>
>>> Fortran IV is mostly the same as Fortran 66.
>>>
>>> And functions and subroutines was (per public sources - before
>>> my time) added in Fortran II in 1958.
>>>
>>> So not quite as bad.
>>>
>>> Anything text sucked big time in Fortran IV/66 but climate
>>> model should not be impacted by that.
>>>
>> It’s possible that, just as today, “seasoned” (I.e. older, perhaps set in
>> their ways) programmers in the 1960’s and 1970’s may not have used
>> new-dangled features like IF/THEN/ELSE or more modern loop constructs. And
>> may actually have liked assigned or computed GOTOs, three-branch IF, etc.
>>
>> Or they may have been constrained by out-of-date compilers on their
>> platforms.
> 
> Here's a statement from NASA GISS regarding Model E.  Which has been
> open source for years, now, if you want to take a look.
> Conceptually like most such models they're simple, pave the earth
> with pizza boxes stacked about 20 high these days, IIRC.  The pizza
> boxes shrink and the number of them that are stacked increase as
> supercomputers increase in power, improving resolution.
> Understanding the model physics is, ummm, a tad more complex :).
> Also some of that increasing power generally is devoted to more
> complex physical modeling which works against how many more pizza
> boxes you can have in your model in reasonable time.
> 
> Anyway, after a prologue pointing out that it has been around
> awhile:
> 
> "While much of the subsequent reworking of the model has led to a
> reduction in these historical influences, some parts of the model
> still hark back to the days of punch cards, FORTRAN 66 and line
> printer output. A charitable interpretation would be that while
> embracing the new (FORTRAN 90/95, multi-processing, netcdf, etc.), we
> endeavour to maintain some of the more harmless GISS traditions
> (which some might call eccentricities) in a spirit of continuity with
> those who have previously worked on the model. On the other hand,
> some of those early decisions (for instance regarding diagnostics, or
> conservation properties) turned out to be very far-sighted and are a
> principle reason why the GISS series of models continue to play a
> useful and important role in the world of GCM simulations."

A quick look at a few randomly selected files from the
code at https://simplex.giss.nasa.gov/snapshots/
did not show very old code - lots of 90 and some
77 upgraded to 90.

Arne