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Scientific/Engineering Calculator

    Language JAVA - SDK1.6
    Version 0.1.6
    Last Update 2009.01.29
Author MathPad Software Corp.


Calculators that use Direct Algebraic Logic are favored by most scientists and engineers over the more common Reverse Polish Notation type of calculator. 
MathPad Calculator has been designed to show one of the possibilities of using Advanced DAL(Dynamic Algebraic Logic) mechanism.


MathPad Calculator supports cut and paste operations input and result data to be exchanged with most spreadsheet and wordprocessing programs.

- DAL(Direct Algebraic Logic) vs. RPN(Reverse Polish Notation)

To add "three minus nine" in your normal calculator you just press the following sequence of keys:

[3] [-] [9] [Enter]

Very simple, right? Now, how would you do the same operation in an RPN(Reverse Polish Notation) calculator? The procedure involves to enter the two operands first and then its operator. This yields the following sequence:

[3] [Enter] [9] [-]

Hewlett-Packard have used the "Reverse Polish Notation(RPN)" since they launched the first scientific pocket calculator, the HP-35, back in 1972. Two of the reasons why Hewlett-Packard decided to use the RPN notation as opposed to the Direct Algebraic Logic (DAL) used on standard calculators were probabily the following: first, RPN is a very efficient way for a chip logic to perform calculations, and second, a technical user, which was the main target for scientific calculators, can perform more complicated calculations with less number of keystrokes, by using this procedure. 

In a normal arithmetic expression, operations are grouped within parentheses to control the precedence of the operations. Segments of the expression which are enclosed within parentheses must be solved prior to continuing with the remaining parts of the expression. Parentheses can also be nested, in which case inner parentheses have precedence and must be solved first. In this case the operators had to be entered by the user explicitly, even though the usual expression involved the implicit multiplication operator. For example, to solve the expression 5X(3-2), the user had the enter the sequence:

[5] [x] [(][3][-][2][)] [Enter]

This can become very inconvenient in RPN mechanism. To overcome this problem, Sharp developed a technology called "Advanced Direct Algebraic Logic(Advanced DAL)," which allows for the user to enter an expression in the same way as it appears in a text on a written document. For example, the expression:

3 tan(45+4^5)

would be entered as:

[3][*] [tan] [(] [4][5] [+] [4] [^] [5] [)] [Enter]

This simplifies significantly the number-entry procedure and constitutes an interesting progress in the usage of algebraic notation within scientific calculators.

Under RPN, the previous expression may be entered as:

[4][ENTER][5][^] [4][5] [+] [tan] [3] [x]

Entering the expression actually implies that there is already a previous understanding on what the expression is doing.


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