eCalc is an easy to use scientific calculatorProgram that supports many advanced features including unit conversion, equation solving, and even complex-number math. eCalc is offered as both an online calculator and as a downloadable calculator.
Input Mode (Algebraic vs. RPN)
The online calculator operates in either algebraic input (default mode) or RPN input. The calculator mode is set by clicking on the “ALG/RPN” symbol in the status bar or by changing the mode inside the menu dialog box.
Algebraic input mode is commonly referred to as “infix notation” and is widely used by most handheld calculators. Expressions entered in algebraic input mode are done in a manner that closely resembles the natural form of the expression and the order of the operations is determined by operator precedence and parenthesis.
RPN, which stands for Reverse Polish notation, is a stack-based notation where operators are designed to follow their operands. For example, to evaluate the expression “1 + 2” in RPN, the user is required to enter “1 2 +” and the expression is evaluated immediately after the operator. Expressions that contain parenthesis, such as “(1+2)*3”, are evaluated by noting the precedence order and entering the form as “1 2 + 3 *”.
Graphical Button and Keyboard Support
The online calculator supports data entry through either a graphical button or through the use of traditional computer keyboard keys. The user is given the option to use either input method and both are equally valid; however, there are some trigonometric function (as noted below) that are limited to computer keyboard entry only since there is a limited amount of space available for graphical button placements.
The stack is a feature of the calculator that provides a way to view a history of results. The stack displays only 4 items at once, but one can scroll up and down the stack by clicking on the up and down arrow above the stack. Values in the stack can also be “popped” down into the input field of the calculator by clicking on the down arrows to the left of the line in the stack.
The calculator is divided into two sections the scientific calculator interface on the left and the calculator pallet on the right. The pallet provides a display area for special features. Some of these features include: Unit Converter, Constants Library, Equation solver, Polynomial Solver, Base Conversion, and Decimal to Fraction Conversion.