April 12, 1994
This is my third installment regarding the scientific
calculator. Today, I only want to attend to a few "brush fires."
New material will wait for the next posting.
Brian
Brian and Steve were kind enough to react to my last posting.
I will "deal" with them in turn. Brian is absolutely right that
the tilde is one of those wandering keys that you can find on any
part of the keyboard. I really didn't have a good rationale for
assigning the tilde to the x-square operator so I devised what I
dow admit to be a lame mnemonic. Nevertheless, wherever the tilde
may be located, I think it is an appropriate assignment for that
operator.
Next, Brian thought that "!" should be used for the logical
"not" operator. I would like for Brian and all of us to keep in
mind that what I am trying to craft is a calculator, not a
computer. Programming a calculator consists of entering decimal
numbers, operators, some parentheses, and a few auxiliary
commands. Programming a calculator and programming in C are
entirely unrelated. As far as the user of a calculator is
concerned, there are no binary numbers in evidence. If you want
to do bit flipping, you'll have to do it somewhere else, on your
own time. On the other hand, finding the factorial of an integer
is very much a scientific operation and should be in the
repertoir of a scientific calculator. The traditional notation
for the factorial is !, which accounts for my assignment of that
character for that operator.
Finally, Brian would like the luxury of using either infix
notation or postfix notation for entering unary operators. In my
view, this would add considerable inefficiency to the calculator
program without making the calculator more useful. I have in mind
a mean, lean calculator that can be loaded high as a TSR out
of the way of other programs. The old calculator consumed about
48K. In spite of the fact that the new calculator has more
functions and is programmable, I do not anticipate that it will
take up much more memory than that.
Steve
I guess that Steve is my next "victim." It is a mistake
to regard a scientific calculator as a souped-up four-function
calculator. A four-function calculator is a data-intensive. Its
purpose is to perform simple arithmetic operations on large
volumes of data. This is why a numeric keypad has keys not only
for the ten digits and the decimal point, but for the four basic
arithmetic operations of addition, subtraction, multiplication,
and division. On the other hand, a scientific calculator is
formula intensive. It requires a relatively small amount of data,
but a large amount of processing via the application of the
formidable array of operators provided. If you use the numeric
keypad with a four-function calculator, you almost never have
to take your hand off this keypad. But if you are doing
scientific calculation, you will need both hands to enter the
various operators at the appropriate time, and you will be taking
your hand off the numeric keypad so often, that its value for
entering numbers vs. the keys on the number row becomes
questionable. A good analogy would be the observation that COBOL,
the business-oriented language, is very good at handling large
amounts of data but poor in the performance of operations other
than the four basic arithmetic ones. On the other hand, C excels
in the performance of mathematical operations of all kinds, but
intensive I/O operations are performed with some difficulty.
I will try to post more substantive matters next time.
Abraham Nemeth, Ph.D.
anemeth@ece.eng.wayne.edu
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