In my past life I was an oceanographer at a consulting company. Essentially we wrote Matlab code that processed data we get from ocean and meteorological models. Many of these models, used by NOAA, are all written in Fortran. While most were well documented, one thing you could not get around is the use of parameters for these models ( think of global variables used everywhere) and a never ending game of go-to statements. I had to figure out how this one flood model worked... literally had to read 5,000 lines of Fortran. This is what we use to determine potential flood impact from hurricanes, today. Software written for oceanography is a whole other beast.
