I googled “FORTRAN Assigning values error” and got result after result after result of hits talking about the errors and pitfalls of assigning values in FORTRAN.
I think using FORTRAN is a symptom of the problem, not the main problem.
Problem is trying to factor in trillions of dollars and how to disperse it (to drug companies and politicians, etc.) as part of the COVID spread model.
That is what is causing the Stack Overflows.
I did the same with C and Java and got the same infinite hits.
The problem is with any computer language.