On Thu, 19 Mar 2020, Mike Markowski wrote:
>> I've been using my trusty HP-42S for so long that I can hardly remember
>> how to use a "normal" calculator :-)
> When my classmate's calculator died during an engineering exam, he asked
> if he could borrow my spare. I handed him my HP 32s and after a minute
> he whispered, "Where's the equals key?" He gave my calculator back.
I did that to a financial controller in a previous life; she was not
amused... Hey, it was the only calculator that I had! I could see her
helplessly looking for the "=" key, then I took pity on her.
On 3/20/20 8:03 AM, Noel Chiappa wrote:
> Maybe I'm being clueless/over-asking, but to me it's appalling that
> any college student (at least all who have _any_ math requirement at
> all; not sure how many that is) doesn't know how an RPN calculator
I'm sure that there are some people, maybe not the corpus you mention,
that have zero clue how an RPN calculator works. But I would expect
anybody with a little gumption to be able to poke a few buttons and
probably figure out the basic operation, or, ask if they are genuinely
> It's not exactly rocket science, and any reasonably intelligent
> high-schooler should get it extremely quickly; just tell them it's
> just a representational thing, number number operator instead of
> number operator number.
I agree that RPN is not rocket science. And for basic single operation
equations, I think that it's largely interchangeable with infix notation.
However, my experience is, as the number of operations goes up, RPN can
become more difficult to use. This is likely a mental shortcoming on my
part. But it is something that does take tractable mental effort for me
For example, let's start with Pythagorean Theorem
a² + b² = c²
This is relatively easy to enter in infix notation on a typical
However, I have to stop and think about how to enter this on an RPN
calculator. I'll take a swing at this, but I might get it wrong, and I
don't have anything handy to test at the moment.
[square root] # to solve for c
Conversely infix notation for comparison.
As I type this, I realize that I'm using higher order operations
(square) in infix than I am in RPN. But that probably speaks to my
ignorance of RPN.
I also realize that this equation does a poor job at demonstrating what
I'm trying to convey. — Or perhaps what I'm trying to convey is
incorrect. — I had to arrange sub-different parts of the equation so
that their results ended up together on the stack for them to be the
targets of the operation. I believe this (re)arrangement of the
equation is where most of my mental load / objection comes from with
RPN. I feel like I have to process the equation before I can tell the
calculator to compute the result for me. I don't feel like I have this
burden with infix notation.
Aside: I firmly believe that computers are supposed to do our bidding,
not the other way around. s/computers/calculators/
> I know it's not a key intellectual skill, but it does seem to me to
> be part of comon intellectual heritage that everyone should know,
> like musical scales or poetry rhyming. Have you ever considered
> taking two minutes (literally!) to cover it briefly, just 'someone
> tried to borrow my RPN calculator, here's the basic idea of how they
I'm confident that 80% of people, more of the corpus you describe, could
use an RPN calculator to do simple equations. But I would not be
surprised if many found that the re-arrangement of equations to being
RPN friendly would simply forego the RPN calculator for simpler
I think some of it is a mental question: Which has more mental load,
doing the annoying arithmetic or re-arranging to use RPN.
I believe that for the simpler of the arithmetic operations, RPN is
going to be more difficult.
All of this being said, I'd love to have someone lay out points and / or
counterpoints to my understanding.
Grant. . . .
unix || die
Moving to COFF ...
On Fri, Mar 20, 2020 at 1:24 PM Grant Taylor via TUHS <tuhs(a)minnie.tuhs.org>
> Would you humor me with an example of what you mean by "thinking on the
> fly"? Either I'm not understanding you or we think differently.
I'll take a stab at it in a minute.
But first, I never cared either way. In college, I had an SR50 and my GF
had an HP45. I would say, between my EE friends we were probably split
50/50 between TI and HP. Generally, it was the RPN centric crew were
fiercely loyal as in the editor wars but would grab whichever was near me
when we all were working a problem set; but I knew a couple of folks that
hated RPN too.
It's possible, because of my undiagnosed dyslexia at the time, but I would
grab the closest calculator, pause to see which is was and then start
entering things as needed. But like Jon -- if I had the TI in my hands, I
found myself copying the equation. I was trying to pay attention to what
button I was pressing to check for any keystroke entry errors. Both types
had all of the same math functions so there was little difference in the
number of strokes, other than not needing parentheses on HP and how you
entered the calculation. With the HP, I was more aware of that equation I
was calculating because I was having to make sure I entered it in the
proper order so I could get the right answer. In my case, I was probably
a tad more careful because I was being forced to thinking in terms of
precedence - but I was thinking about the equation. Whereas with the TI I
was just hitting the button per the equation on the paper. I typed a tad
faster on the TI than the HP because I was not thinking as much but ... I
probably made more typing errors there because I thought less about what I
Aside: I'm sending this reply to TUHS where the message that I'm
replying to came from. But i suspect that it should migrate to COFF,
which I'm CCing.
On 3/20/20 5:48 AM, paul(a)guertin.net wrote:
> I teach math in college, and I use an RPN calculator as well (it's
> just easier).
Would you please elaborate on "it's just easier"?
I'm asking from a point of genuine curiosity. I've heard many say that
RPN is easier, or that it takes fewer keys, or otherwise superior to
infix notation. But many of the conversations end up somewhat devolving
into religious like comments about preferences, despite starting with
honest open-minded intentions. (I hope this one doesn't similarly devolve.)
I've heard that there are fewer keys to press for RPN, but the example
equations presented have been effectively he same.
I've heard that RPN is mentally easier. But I apparently don't know
enough RPN to be able to think in RPN natively to evaluate myself.
I dabble with RPN, including keeping my main calculator app on my smart
phone in RPN mode.
So I am genuinely interested in understanding why you say that RPN is
> Sometimes, during an exam, a student who forgot to bring their
> calculator will ask if they can borrow mine. I always say "sure, but
> you'll regret it" and hand them the calculator. After wasting one or
> two minutes, they give it back.
> (Note that I always make sure no calculator is needed for my exams,
> but it's department policy to authorise non programmable calculators,
> and it seems to reassure students to have the calculator on the desk,
> so I don't mind.) >
Grant. . . .
unix || die
As many of you may be aware, Bruce D. Evans <bde(a)freebsd.org> died in
mid-December. I am currently looking through his digital estate on
behalf of his family and the FreeBSD Project.
I have discovered that he kept an extensive collection of 5¼" floppy
disks. I haven't looked through them but they appear to include
things like OS-9 and Hitachi Peach files (and presumably Minix stuff,
though I haven't found any of his Minix work). He also has a
selection of newletters from an Australian Peach users group. Is
there any interest in this material from a historicial perspective?