I remember when I was a junior engineer working on aerospace simulation software (defense contracting). I was primarily writing C++, but we had a large collect

I remember when I was a junior engineer working on aerospace simulation software (defense contracting). I was primarily writing C++, but we had a large collection of physics algorithms written in Ye Olde FORTRAN that we had to link in. I brought up a possible rewrite, and one of the greybeards told me that they had looked at that in the past, but the govt V&V process on any rewritten algorithms would have been so onerous that they eventually dropped the idea. The last guy who actually understood that old code retired about a year after I started there and then things started to get... interesting. As an aside, for 'new' code, I'm actually ok with the science folks dumping a pile of matlab script on me so I can rewrite it in Python, Java, etc. (rather than letting scientists write production code, which I'll have to rewrite later anyway).