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] []
HewlettPackard have used the
"Reverse Polish Notation(RPN)" since they launched the
first scientific pocket calculator, the HP35, back in 1972. Two
of the reasons why HewlettPackard 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(32), 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
numberentry 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.
