Round 2 of 4 - Algebraic vs RPN - Eq. Resistance

In no way intended to be an end-all-be-all to the ongoing discussion -- this series of videos simply explores how efficiently an expression can be entered in Algebraic (in-fix) vs RPN (post-fix) calculators.
I attempted to be efficient, and in some cases explored various ways to enter the expression (particularly on the Algebraic calculators) ahead of time. However, the goal was NOT to determine the absolute fewest number of keystrokes possible -- instead, it was to attempt to use each calculator in a manner consistent with the way someone familiar with the device might use it.

[@christernilsson1]

Having defined a parallel key P, the solution will be: 3 Enter 5 P 15 P That is seven keystrokes. P = 1/x swap 1/x + 1/x Would be nice to see a comparison network of ten resistors.

[@scottcollins7513]

TRUE. Once you start tapping into the programming abilities of the HP28S, it is a different comparison. Such a great calculator.

[@cret859]

Nice ! Another efficient RPN entry is obtained using the HP-15C or any of the other RPN from the Voyager's serie since, as the HP-48Gx, they have a direct [1/x] key. HP-15C really need only 10 keystrokes (including any prefix-key and all press for digit) : 5 [1/x] 3 [1/x] 1 5 [1/x] [ + ] [ + ] [1/x] In comparison, HP-28S need extra keystrokes because the 1/x operation is on a prefix-key : 5 [ ][1/x] 3 [ ][1/x] 1 5 [ ][1/x] [ + ] [ + ] [ ][1/x] need 14 keystrokes !

[@scottcollins7513]

You can, though, assign the 1/x key to the custom menu, which makes it unshifted. This would make sense if you used it often enough. Thanks for the comment, C Ret.

[@parragoriouse0138]

casio farred really well on this

[@antoniobastianacci2017]

With the HP-20S (infix notation): 5 1/x + 3 1/x + 15 1/x = 1/x (10 keystrokes)

[@scottcollins7513]

That is impressively efficient. Thank you for leaving a comment and for bringing this calculator to my attention -- I know nothing about this calculator, so I plan to watch some videos on it. Cheers.

[@KrazyCouch2]

I'm not sure about the others but I know you can get the HP Prime down to 15 if you type 1/ first.

[@scottcollins7513]

I mentioned it in the description, but I was trying to just use the calculator in a way that seemed most natural rather than with with goal of minimizing keystrokes. Though, if you were doing a ton of any of these types of problems, most of us would gradually improve our approach (i.e. seek to decrease keystrokes). Thanks for the feedback.

[@KrazyCouch2]

@@scottcollins7513 That makes sense. I probably should have read that first.

[@AntonioCavicchioni]

I like the music... Very programming inspiring...

[@scottcollins7513]

Thanks!

[@chef1arjunaidi]

Hi Scott. In the HP Prime example, your calculator was in the algebraic mode in CAS, so you cannot say that the Prime is using RPN. Best use the Prime in RPN mode, calculations in the Home key command line. I reckon that there is a total of 13 steps to reach the answer :-). btw, the 48G won with 10steps simply because the inverse key 1/x is a button, whereas it is a shifted function on the Prime. Thanks for the interesting videos that you produce. Are you under lockdown? ;-)

[@scottcollins7513]

Hello there. Thanks for the feedback. I left the Prime in Algebraic mode b/c I think that is how most people will use it. And, yes, the 48GX won that round b/c the shift was not required, but a good keyboard layout which places the most-used functions as "non-shifted" should be rewarded. We are in partial lockdown (but, I still sometimes make these nerdy videos even when we are not). It seems like if you are doing a lot of RPN you would be better off with a calculator that does it natively (e.g. HP50). The Prime is probably capable, but I do not even know how you Swap the stack on the Prime in RPN mode since there is no obvious button to do so.

[@VeridicusX]

@@scottcollins7513 It's the comma button beside "Enter". (A stack entry has to be highlighted.)

[@VeridicusX]

"A stack entry has to be highlighed" - I should say, "A stack entry has to be active." If you've made a syntax error or something, then the stack may lose focus.

[@scottcollins7513]

@@VeridicusX Good to know. Thank you.