I'm going "holy crap!" at what you can do with LibreLogo for diagram
generation.
https://commons.wikimedia.org/wiki/Category:Images_with_LibreLogo_source_co…
http://conference.libreoffice.org/talks/2013/content/sessions/054/files/lib…
I might have to use this more. Last calculated diagram I did [*], I
figured out the positions of each dot with a calculator and
hand-edited the SVG.
[*]
https://commons.wikimedia.org/wiki/File:StarOffice_major_derivatives.svg
- d.