Shark Movement help

I download an example from SGI corporation named atlantis.zip,but I didn’t understand the code and arithmetic,where can I access some documention?

The code is real simple. The sharks have a sine wave running down them as they are translated forward (and perhaps some other simple deformations, as they turn). It was written by Angus Henderson in IrisGL years ago and ported to OpenGL later by someone who removed his credits.