sometimes the code is deeply complex stuff that has accumulated for over 30 years. to _just_ rewrite it in CUDA can be a massive undertaking that could easily produce subtly incorrect results that end up in papers could propagate far into the future by way of citations etc
That's the complete opposite of what is actually the case: some of that really old code in these programs is battle-tested and verified. Any rewrite of such parts would just destroy that work for no good reason.
Why don't YOU take some old code and rewrite it. I tried it for some 30+ year old HPC code and it was a grim experience and I failed hard. So why not keep your lazy, fatuous suggestions to yourself.
Sounds like a -terrible- job for LLMs, because this is all about attention to detail. Order of operations and specific constructs of how floating point work in the codes in question are usually critical.
A human has to have the knowledge of what the code is trying to do and what the requisites are for accuracy and numerical stability. There's no substitute for that. Having a translation aid doesn't help at all unless it's perfect: it's more work to verify the output from a flawed tool than to do it right in this case.
