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Why are most climate models in Fortran?

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Re: Why are most climate models in Fortran?

#51

Post by simplicio »

Another advantage to Fortran in academic settings, at least the older version of Fortran, is that there isn't much to the language. Someone already familiar with programming can pick it up in a day or two.

So if your a Prof with a large code-base that you want to have a stream of Grad-students, undergrad research assistants, assoc. Profs etc. contribute to before they move on, having a language that doesn't require squandering half a semester on learning to code before you can start doing actual science is a big bonus.

Re: Why are most climate models in Fortran?

#52

Post by busterarm »

Hankenstein2 wrote: post #13

I work at one of the labs mentioned and get paid for running not only the climate models but mesoscale models as well, which are also written in Fortran. The premise of the article is that Fortran, 70 years later is still an appropriate tool to use for crunching numbers which it absolutely is but it neglects one major problem. Like the COBOL issue that was all the rage 20 years ago, it is difficult to hire younger ge…

> I work at one of the labs...

> ...it is difficult to hire younger generation programmers that want to and are excited to develop in Fortran.

How much are you paying? Most often times I see this kind of reasoning, digging deeper shows that the salaries are not competitive. There's a large number of us that just want to work on interesting problems for adequate money and don't care what the toolset is. I'm fully on board with the idea of being paid to write Fortran.

Also, COBOL's problem isn't so much that younger generations aren't excited about it, but that the problems in the domain solved by COBOL all require highly specialized domain knowledge about an obtuse set of systems said code runs on (with most of their documentation paywalled, at least until recently). The barriers to entry are much, much higher and few companies are willing to train at the rates the language demands.

Re: Why are most climate models in Fortran?

#53

Post by arkipelago »

Hankenstein2 wrote: post #13

I work at one of the labs mentioned and get paid for running not only the climate models but mesoscale models as well, which are also written in Fortran. The premise of the article is that Fortran, 70 years later is still an appropriate tool to use for crunching numbers which it absolutely is but it neglects one major problem. Like the COBOL issue that was all the rage 20 years ago, it is difficult to hire younger ge…

I was part of a project looking at the feasibility of migrating some of the EPA's air pollutant exposure models from Fortran to R/Python. While Fortran was decisively faster, I think the project lead recommended migrating the model to R since not many people used Fortran anymore. It was also harder to share Fortran code for collaboration as well.

Re: Why are most climate models in Fortran?

#54

Post by milancurcic »

thelastestate wrote: post #23
Hankenstein2 wrote: post #13

I work at one of the labs mentioned and get paid for running not only the climate models but mesoscale models as well, which are also written in Fortran. The premise of the article is that Fortran, 70 years later is still an appropriate tool to use for crunching numbers which it absolutely is but it neglects one major problem. Like the COBOL issue that was all the rage 20 years ago, it is difficult to hire younger ge…

My understanding is that they're mostly fortran programs linked together with unix scripts which are run on HPCs - could the models run in a more distributed way like high quality grid computing setup? Lastly, what's the best way to find and learn more about the models?

Yes, they run in the cloud, see e.g. https://cloudrun.co (disclaimer: my side-business), but others have done it as well, for a few years now. On dedicated, shared-memory nodes, it's no different from HPC performance-wise. It can be even better because cloud instances tend to have later generation CPUs, whereas large HPC systems are typically updated every ~5 years or so. But for distributed-memory parallel runs (multi-nodes), latency increases considerably on commodity clouds which kills parallel scaling for models. Fortunately, major providers (AWS, GCP, Azure) have recently started offering low-latency interconnects for some of their VMs, so this problem will soon go away as well.

Re: Why are most climate models in Fortran?

#56

Post by yodelshady »

cbkeller wrote: post #14

High performance scientific computing is very much still a FORTRAN, C, and C++ game. And of those, FORTRAN has some compelling advantages in terms of first-class built-in support for multidimensional arrays, and quite excellent compilers. And, as others have noted, until the `restrict` keyword in C99, there were optimizations in FORTRAN that were not even possible in C. I mostly used C for my (small-scale) HPC work i…

Open question: why are multi-dimensional arrays, and matrices specifically, so neglected in almost every other language?

They map well to practically freakin' everything, for what seems like.. not that much effort on the language design side, but an enormous amount of tedious, duplicated effort on the user side.

Re: Why are most climate models in Fortran?

#58

Post by hntrader »

yodelshady wrote: post #56
cbkeller wrote: post #14

High performance scientific computing is very much still a FORTRAN, C, and C++ game. And of those, FORTRAN has some compelling advantages in terms of first-class built-in support for multidimensional arrays, and quite excellent compilers. And, as others have noted, until the `restrict` keyword in C99, there were optimizations in FORTRAN that were not even possible in C. I mostly used C for my (small-scale) HPC work i…

Open question: why are multi-dimensional arrays, and matrices specifically, so neglected in almost every other language? They map well to practically freakin' everything , for what seems like.. not that much effort on the language design side, but an enormous amount of tedious, duplicated effort on the user side.

This is a great question and I hope you get an answer to this.

The number of woeful ad-hoc solutions I've seen to people handling matrix data in Java/C# for what should've been otherwise very basic analysis ...

Something with pandas-like capability in a lower level language would be amazing.

Re: Why are most climate models in Fortran?

#59

Post by saboot »

hilbert42 wrote: post #3

1. There are thousands of scientific subroutines written in Fortran that are stable and well tested - in fact, there are well established formal libraries of them that go back over 60 years. The researchers know and trust them. 2. Despite the sneers and derision that Fortran has been subjected to from non-Fortran programmers over recent decades, Fortran is an excellent language to do intensive scientific and mathemat…

Researcher in Nuclear Engineering chiming in with a similar experience. Much of our code is the same way, and in fact our field more or less invented many computing methods used today. One widely used simulation code called MCNP [1] can trace it's origins back to running on the ENIAC at Los Alamos in the 40s(!). At some point, it was considered a major upgrade when it was rewritten into fortran90.

[1] https://en.wikipedia.org/wiki/Monte_Carlo_N-Particle_Transpo...

Re: Why are most climate models in Fortran?

#60

Post by nnm »

hntrader wrote: post #58
yodelshady wrote: post #56

Earlier quoted context omitted.

Open question: why are multi-dimensional arrays, and matrices specifically, so neglected in almost every other language? They map well to practically freakin' everything , for what seems like.. not that much effort on the language design side, but an enormous amount of tedious, duplicated effort on the user side.

This is a great question and I hope you get an answer to this. The number of woeful ad-hoc solutions I've seen to people handling matrix data in Java/C# for what should've been otherwise very basic analysis ... Something with pandas-like capability in a lower level language would be amazing.

Every time I was forced to pandas I miss R data.frame and data.table.
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