My first cut at fun math stuff for sci/eng types, including a reworked and much better tested version of the double dispatching math stuff has showed up at the UIUC arhcive ftp://st.cs.uiuc.edu/Smalltalk/Squeak/goodies/EngineeringMath/.
For an overview and more detailed description, read ftp://st.cs.uiuc.edu/Smalltalk/Squeak/goodies/EngineeringMath/EngineerMath.html.
Travis Griggs