On Sun, 18 Apr 2004 08:39:04 -0700, "Robert Swinney" wrote:
Gary sez:
" As John noted, RPN works exactly the way you'd do the calculations with
pencil and paper, so it is a natural and familiar way to work for people
who
are comfortable with doing hand calculation. "

I will have to agree, as I often begin calculating in the middle of a
lengthy expression. Problem is, you have to record the interim results and
some care is required to maintain those results. I can do it, but it is so
much easier to begin at the beginning and enter things sequentially in AE.
Thanks Gary, I didn't realize RPN was a product of the 20s. It would seem
that for really lengthy calculations, RPN would be a labor saver.

It is a labor saver, and you don't need to record interim results, they simply
automatically get pushed on the stack as you continue to calculate, and
automatically pop off the stack when you're ready to use them. That's the
real power of postfix notation.

With an AE style calculator you have to be careful how you attack a problem.
There are many times when you get stuck, have to store an intermediate result
in memory, clear the calculator and start what is essentially a new calculation.
That virtually never happens with a RPN calculator. No matter the order in which
you tackle a problem, there's almost always a way to do it without storing
intermediate results in memory and restarting.

Of course for simple 2+2 stuff, RPN doesn't offer any real advantages. It is
when you start doing complex calculations that the labor savings, intermediate
results sanity checking (IMHO the most important feature), and the ability to
attack the problem in any order really starts to be of benefit. That's why RPN
calculators are such a favorite with older engineers who started out with pencil
and paper or slide rules. They're used to doing sanity checks as they progress
with a calculation. AE style calculators don't lend themselves to that.

Of course nowadays people expect computers to hand them an answer without
any thought on their part. It is just plug in the numbers and wait for the result.
That's all well and good for canned solutions to known problems, but it is less
satisfactory for calculating answers to new or unique problems. You're depending
on the author of the software to have gotten it right. That's not always obvious.
For example, the early Windows calculator gave erroneous results because it
incorrectly rounded internal intermediate results. People didn't immediately
catch that because the AE style offers no way to do sanity checks on intermediate
results. They remain hidden from view.

Gary