Message #25 Posted by bill platt on 14 July 2004, 8:51 a.m.,
in response to message #8 by Valentin Albillo
Thanks for the humorous feedback.
BTW, my old colleage, a German, whom I worked with in 1998, had a machine that looked very much like your Sharp models---I remember that it was a BASIC programmable----but I cannot remember whether it was a Sharp, or a Casio. Did Casio make devices similar (with the landscape layout and metal bezel) to the Sharps?
I remember that he sort of frowned or smirked when he saw my HP 32sii---his machine was certainly more powerful than mine!
On a more academic (serious) note, you asked, with regard to consistency and logic,
And, by the way, would you care to elaborate which of those don't apply to true, formula entry algebraic systems?
Yes, indeed, there are many inconsistencies to mention. The largest inconsistency is merely that different models have different rules for basic operations.
But others are merely annoying:
HP 32sii equation list (an algebraic exression evaluator)
the +/- key is required for second arguments
of two number functions, viz %chg(200 -150)
whereas the minus operator can (or should? can't
remember!) be used in other positions.
HP business calculators, e.g. 17bii, there are parenthesis
but no precedence. However, in the solver,
parenthesis do have precedence.
Some machines do "implict multiplication" and some do not.
On the HP 33s, you can use "implicit
multiplication" in the ALG command line, but not in
the equation list.
Many "formula entry" machines have an input buffer length
limit, including both the HP 30s and the Casio
fx-115ms: 80 characters. The long expression
you posted about a week ago just barely fit in
those machines. The formula machines *without*
a recallable input buffer do not have this
problem, as they evaluate intermediate results---
but some are confusing to understand regarding
many of the functions correct actions--especially
troublesome are negatrive exponents.
There are really two major categories of "Algebraics":
1. "traditional" algebraics like the hp 20s, TI 30,
etc. These are actually postfix (like RPN) for
all "one number functions", and infix for the
arithmatic operators. Parenthesis and pending
operations are implemented.
2. "Formula Entry" algebraics, which attempt--not
always successfully--to implement "type in your
expression just like it is on paper." "DAL",
"S-VPAM" and "Formula" are some of the names
for these systems.
You will notice that I find inconsistent behavior on (gosh!)
HP machines. No manufacturer is immune to this.
The fact is that when there is an actual formula to work from--an equation or expression which is written down, the ability to put a formula into an input buffer which is recallable after evaluation, is superior to RPN. I really like RPN. It is definitely fast. But, if you can check your input, and more importantly recall it---then that is better in almost all circumstances. Except that experienced arithmeticians (is that a new word?!) find no need for recalling much of their work.
BUT--and this is important---in all my years of exclusive RPN usage, although I could trust the keypresses etc., for any calculation that mattered, I would always DO IT TWICE! Why, because if you are an engineer and not just a hack, you better be sure you get it right!
For an interesting comparison to this RPN/formula business:
When I first discovered spreadsheets, I was blown away by them. I was like, "wow!!!!!!!" And you know, most anything that I used to do on a calculator went onto the spreadsheet. Spreadsheets are especially useful for those dreadfully tedious computations that the naval architect routinely encounters: weight-moment computations. The spreadsheet makes it possible to type in all your input, check it, and get an answer.
Of course, as the size and complexity of the spreadsheet increases, it becomes dangerous. Then, a database approach becomes much more reliable.
However, through all of it, the calculator remains an indispensible tool for checking the formulas! (For instance, I used the programmability of my hp 11c to write a weight-moment program which is very handy for checking---I originally wrote it before I had a spreadsheet!).
The realy driving force behin the "Formula" calculator is memory. All of our favorite HP handhelds up until the 41c were very tight on memory. RPN was especially suited to low-memory---as very little is kept in memory!
But once you have gobs of memory available, then there is no reason why you shouldn't keep a lot of input data.
I think I am arguing strongly for the Formula design, aren't I?
In fact, I like the RPL concept of algebraic objects on an RPN stack---that is very powerful and flexible.
What makes the HP machines (up through the Pioneers) good is not so much the RPN, but rather the combination of good tactile feedback, programmability, well thought-out layout, and thorough manuals, in that order.
I am not sure that there are any keystroke programmable calculators in production now, from any other manufacturer.
Edited: 14 July 2004, 9:06 a.m.