From Big Angry Dog:
DreamCalc Professional is the Ultimate Free Scientific and Financial Graphing Calculator for Windows. This slick math application is so realistic, you'll never reach for your hand-held calculator again!
Not only does DreamCalc give you an intuitive and almost tactile experience, it is a fully featured graphing calculator that can graph functions and plot list data in an instant (no more setting up spreadsheets). In fact, it is a match for many dedicated graphing packages, but far easier to use.
DreamCalc offers a full range of scientific functions, statistics, complex numbers, base-n logic, unit conversions, numerical calculus and built-in constants and a powerful polynomial solver. Select from Reverse Polish Notation or pre-fix or post-fix algebraic input, and with the optional ability to run in your Windows system tray, DreamCalc will always be there whenever you reach for a calculator.
The Professional Edition also offers financial and extended graphing features, including: TVM registers, BOND, IRR, MIRR and amortization functions.
DreamCalc is free for non-commercial use. Premium features, such as graphing, require a paid upgrade. Ten percent of sales go to charity.
Look for DreamCalc on Youtube.
What's new in this version:
DreamCalc is now free for non-commercial use. Premium features, such as graphing, require a paid upgrade. Other changes include voice accessibility and user interface improvements.