Set Helper is a program I wrote way back in 1997 to calculate Interval Vector and Forte Number for artibrary pitch-class sets. See this wikipedia article for more information about pitch-class sets.
This was my very first Java program, and although it works it isn't really great code. But someone might find it worthwhile to glance at perhaps. It was originally an Applet, and I converted it to a standalone app before uploading to GitHub. There is also a clickable jar file if you're interested in running the program directly.