TTCalc

TTCalc is a mathematical calculator. It has a nice user interface,
formulas for calculating can be inserted by using a keyboard or a mouse.
The result is automatically shown in a second window without using any
additional keys such as 'equal'. The program possess trigonometric
functions, inverse trigonometric functions, hyperbolic functions,
logical operators, logarithms, functions for converting between degrees
and radians and so on. Additionally the program allows the user to
define his own variables and functions. Calculations are performed by
using floating point numbers with three kind of precision, the biggest
has 288 bits for its mantissa and 96 bits for its exponent that is
about 2.551...e+11925026709067095507636213441 with 85 valid decimal
digits. The program independently allows to insert and display values
with the base (radix) from two to sixteen. 

Author: Tomasz Sowa <t.sowa AnTispam slimaczek.pl>
Project page: http://sourceforge.net/projects/ttcalc
Licence: BSD (open source)