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10.4: Be aware of a Calculator widget bug
Authored by: dcipjr on May 24, '05 10:52:50AM

This is exactly why I use RPN instead of standard algebraic notation.

If you want (1+2)*3, you type 1 [enter] 2 + 3 *

If you want 1+(2*3), you type 1 [enter] 2 [enter] 3 * +

It's a far superior entry system that is actually more intuitive once you get used to it. I don't understand why people insist on the old algebraic notation, with all its ambiguities. There is no order of operations (or parenthesis) in RPN, and the stack makes life so much easier.

Anyway, I digress. Apple thankfully included RPN in its Calculator app in OS X, but there is no button to let you swap the top two values in the stack, and no roll up/down buttons so that you can roll the values in the stack. That severely limits the benefits of using a stack, and I hope Apple builds in these capabilities soon.

Until then, I'll stick with my HP calculator, although the RPN Calculator Widget is a step in the right direction.

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10.4: Be aware of a Calculator widget bug
Authored by: diamondsw on May 24, '05 11:55:01AM

Intuitive? Huh? I'll agree that it's non-ambiguous, but intuitive, no. When I see 1+2*3, I think "One plus two times three", and that's how I expect to punch it in. I do not think "One Two Three Plus Times", so RPN is not intuitive; non-ambiguous, sure, but not intuitive.

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10.4: Be aware of a Calculator widget bug
Authored by: colter on May 24, '05 12:18:24PM

It's not necessarily unintuitive, it's just different from what we're taught in school. I learned RPN when I got an HP 48-GX for college, and I've never looked back. The appeal of RPN entry is that it's simpler and, as you said, not ambiguous. You first provide the data you're working with and then specify what you want done with that data. It comes down to personal preference; I think it's easier to work in RPN.

You're doing the same thing, whether it's written as infix or postfix notation. One way, you learn to resolve operations in PEMDAS order. The RPN way, you learn to do it as you go.

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10.4: Be aware of a Calculator widget bug
Authored by: gleam on May 24, '05 01:21:52PM

Actually, in RPN, if you wanted to do 1+2*3 you would do 1 2 3 * +.

Well, I would do 2 3 * 1 +, but that's me.

I don't think either is more or less intuitive. You think 1+2*3 is more intuitive because you grew up seeing it written out as 1+2*3. If you'd seen it written out 1 2 3 * +, you'd think RPN was intuitive. It's all stuff you learned at some point, you didn't innately know that + meant plus, for instance.

Anyway, on calculators the big advantage of RPN is that it saves you keystrokes.

An example:

you want to calculate ((2*8)+(9*3))/((1/7)-(5*9))

That's pretty much how you have to write it on most non-rpn calculators. you might be able to eliminate a parenthesis or something, but otherwise you're left to type in all that crap.

RPN: 2 8 * 9 3 * + 1 7 / 5 9 * - /

14 keystrokes vs 28. As the complexity increases so, generally, do the savings from using RPN.

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10.4: Be aware of a Calculator widget bug
Authored by: jlaro on Sep 30, '05 09:07:32PM

Actually, it's 19 vs 19 keystrokes, not 14 vs 28. For the RPN you forgot to count the ENTERs between values (otherwise 2 8 is 28), and for non-RPN there were too many parenthesis as you said (and the last one can be dropped because = closes it automatically).

I admit, I never used an RPN calculator before writing this post. The big difference seems to be that with RPN you have to memorize which groupings interact with which, and how, to put operations at the right place, whereas with the normal method the machine does it for you if you follow exactly the written equation (with SOMETIMES extra parenthesis to make sure the machine understands correctly).

Question to RPN experts, how would you enter the quadratic solutions (-b+SQRT(b^2-4ac))/2a and (-b-SQRT(b^2-4ac))/2a ? I tend to think that a lot of memorizing is necessary.
24-keystroke non-RPN example: ( - 2 + ( 2 x2 - 4 * 3 ± * 8 ) SQRT ) / ( 2 * 3 ± =

I guess it's just like reading sheet music, anybody can get used to anything.

(somehow ± can be shown here, but not the square root sign, hence my use of SQRT)

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Authored by: MJCube on May 24, '05 03:17:54PM

"more intuitive once you get used to it" is a contradiction. To me 'intuitive' applied to software means it works the way you expect the very first time, and you don't have to get used to anything.

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Authored by: raider on May 26, '05 09:28:24AM

Exactly. Freaking "rocket science" is intuitive if you are a rocket scientist...

I have been using a mouse for almost 20 years now, and I can't imagine anything simpler. But the mouse confused the heck out of my 70 year old stepmom who had never touched a computer (not even an ATM) in her life... She would lift the mouse up off the table to move the cursor up. To her - UP was UP! Not Up was Forward....

It is all relative.

I say that RPN is annoying as hell. So I don't use it. That is the beauty of our world. We use what we want... I would rather use the 28 keystrokes and make something that looks usable than use less and make it cryptic and confusing to 90% of the people who look at it... But if RPN is nice for you, by all means - use it...

Just like the two button mouse.

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