HP48GX User Guide Cover Plot

[BruceH]

In the absence of other replies I'll chip in my 2p.

I don't think it is an equation plot - at least not in the sense of using one of the built-in tools to graph it. It looks to me more like a graphic generated by a program and so your question becomes: hows does the program generate that 'graph'?

There are probably several ways to do it. One would be to generate a matrix of a uniform 2d grid and then distort the grid by multiplying by matrices. (Folding the grid up into a U shape first; then wrapping the result around the outside of a 'wheel' would seem to be a good start.)