But any system I use, whether it be Macsyma, Mathematica, Lisp, or OCaml, had better have the facility of drawing graphs to help me visualize the solutions to my problems. And all the extant systems out there require the production of CSV files, or spreadsheets, in order to feed them data for plotting. I wanted a more direct means, and that's why I created the Lisp Plotter package.

I have been using that package for more than 20 years now. It has evolved over time, but it has been stable now for nearly 6 years. About the only time I look at the source code is when I have a question about some esoteric plotting option that I gave it. The last big cleanup took place after LW 6 was provided, because CAPI had changed ever so slightly. It gained the ability to draw text strings at arbitrary angles, and that allowed a big simplification in the Plotter code. I had been doing that myself by rotating bitmap images of the characters.

Right-clicking the mouse in a graph should bring up a context menu where you can plant some fiducial marks for allowing relative measurements in X and Y. Left clicking should bring up a tooltip showing those relative measurements. I find that the latest version of CAPI on both OSX and Windows now makes those tooltips a bit too transient for my taste.