I worked at an Airline in late 80s working on numerical optimization code in fortan / IBM mainframes - integer optimization with maybe 10k rows and 10m+ columns

I worked at an Airline in late 80s working on numerical optimization code in fortan / IBM mainframes - integer optimization with maybe 10k rows and 10m+ columns. I remember they having specialized vector processors to run those optimizations. We used to run those schedule optimizers daily until it was time to hand it over to the next planning department. The firm also had a in-house team from IBM for help with it. Anyway the urban myth in the IT dept was, they had a custom fortan compiler written in early 70s that saved the firm from buying 2 additional IBM mainframes with the compiler writer compensated well