The calculator is being provided in several versions, depending on the tasks to solve.
http://www.c4calc.com
Calculator and numeric system supporting permanent installation of user defined functions and libraries.
http://members.aol.com/rf21exe/
Javascript general-purpose calculator and some special-purpose applications.
http://www.geocities.com/Vienna/Strasse/7722/math.html
Scientific calculator with many features including Paper Trail. Windows32. Free trial download.
http://www.esbconsult.com/esbcalc/esbcalcpro.html
A full-function scientific calculator for Windows. Trial download.
http://fp.syberad.plus.com/calculator/calculator.htm
Free software calculator with scrolling tape, financial mode, fractional number (e.g. 1 3/4), and other advanced features.
http://www.akapa.com/calculator.html
Calculator program for the Nokia 9210/9210i/9290 Communicator: also PC/Windows. EPOC version for sale by post, Windows version is postcardware.
http://personal.inet.fi/business/vstt/index_eng.htm
Glossary of terms. Material ranges from undergraduate to research level.
http://mathworld.wolfram.com/