Click here to download the latest version of GFC.
In late March 1997, I began to ask the question "How far is it from here to there?" I did not realize how insidiously difficult this question was to answer. Like any geek worth his weight in salt, I began to surf Internet for other souls who may have asked (and hopefully answered) this same question. I soon happened upon source code for doing these calculations. I finally settled on Fortran code at NOAA since traffic on the newsgroups seemed to say this was the most accurate of the programs. Not knowing Fortran, I began to read the code. I then found out about something called an ellipsoid. Not having any math since Algebra in high school, I started doing some research and came to the same conclusion as Barbie, "Math is hard."
Now that I was onto this ellipsoid thing, I started reading my wife's calculus, trigonometry and engineering mathematics textbooks. Did you ever see the "Darmok" Star Trek: The Next Generation episode? This is where Picard and the captain (named Dathon) of an alien vessel are on a planet together but can't understand each other even though they understand every word each other says. Dathon kept saying "Darmok and Jilad at Tenagara!" which thoroughly confused Picard. I am firmly convinced the writer of this episode got the idea after getting into a conversation with two mathematicians. Not being one to let a little ignorance get in the way of progress, I hit the books and pestered many non-ignorant people with lots of questions. Slowly (and painfully) I began to understand what was going on. As Dathon would say, "Sucat, his eyes uncovered!" GFC is the sum total of what I have learned. As I learn more I will add it to GFC. When you look at the source code, if a variable name is not a word, it is something I don't understand (yet).
Thanks to LCDR L. Pfeifer and John G. Gergen for writing the Fortran programs that made GFC possible. And thanks to NOAA for putting their source code in Internet.
Sam Blackburn