FourLevel RPN and the Real World  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: FourLevel RPN and the Real World (/thread258508.html) 
FourLevel RPN and the Real World  Matt Agajanian  12122013 Hello there. Please humour me on this one. After seeing the posts about the Batman graph posted here a few weeks ago and the fact that the WP34S can be configured with an 8register stack, I got to wondering about just how complex the equations in the physical, biological, medical, etc. sciences really are. So, with that said, just how is it that four levels of an RPN stack are sufficient for application and usage in the mathenatics for the sciences?
Or, are the mathematics in the sciences not that complex being that everthing from the HP65 to the HP41 and afterwards has sufficed for use in the real world? Edited: 12 Dec 2013, 4:49 p.m.
Re: FourLevel RPN and the Real World  Walter B  12122013 Hi there, Quote:They aren't. They are sufficient for the majority  but I've experienced problems every once and a while requiring at least five levels. Presumably six levels would catch all problems worked inside out. The reason why the WP 34S features eight levels is complex domain.
d:)
Re: FourLevel RPN and the Real World  Geir Isene  12122013 A 4level RPN stack + a couple of storage registers does the trick
Re: FourLevel RPN and the Real World  Matt Agajanian  12122013 Please enlighten me. Just what range of calculations are you speaking of?
Re: FourLevel RPN and the Real World  Raymond Del Tondo  12122013 Quote:"A couple of storage registers" simply means missing stack levels. Not a problem with a virtually unlimited stack;) Re: FourLevel RPN and the Real World  Geir Isene  12122013 Except there are advantages to have storage registers in certain situations where a virtually unlimited stack is cumbersome and lacking the neatness of the 4level stack. And so I really do prefer the HP41 over the RPL machines like the 48  from simple calculations to really complex ones.
Re: FourLevel RPN and the Real World  Raymond Del Tondo  12122013 Quote:As written above, not a problem with a virtually unlimited stack. You can limit stack usage as you like, and you can use variables and "register" arithmetic for calculations in combination with an unlimited stack, too.
With an unlimited stack, you are just not...ahem, limited;)
Re: FourLevel RPN and the Real World  Geir Isene  12122013 Still there are many times I would prefer the Tregister behavior of a 4level stack and that it rolls around on only four levels. The use of fixed registers is of course a feature beyond the stack in that they are... fixed :)
Re: FourLevel RPN and the Real World  Walter B  12132013 So an eight level stack is a good compromise: featuring Dlevel repetition AND high enough four all formulas.
d:)
Re: FourLevel RPN and the Real World  Gerson W. Barbosa  12132013
Quote: ^^^^The spelling might indicate an unconscious preference for the superior 4level stack :)
Re: FourLevel RPN and the Real World  Nick_S  12132013 Your RPN formulae can address registers of which there are 67 in an HP15C, for example. These can be used to represent the variables in more complex calculations with intermediate storage when more than a couple of stack levels are required.
Edited: 13 Dec 2013, 6:32 a.m.
Re: FourLevel RPN and the Real World  Walter B  12132013 So sorry, Mr. Freud ;)
Re: FourLevel RPN and the Real World  Gene Wright  12132013 Yes, it IS a very good compromise. Just one of the many excellent design decisions made in the 34S.
Re: FourLevel RPN and the Real World  Marcel Samek  12132013 If I am just evaluating an equation and entering values in as necessary, then a 4 level stack can be sufficient for quite complex equations. However, if I enter values that are then reused in the equation multiple times, it is a different story. In the first case, you are using the RPN stack to perform operations and hold intermediate results, which it is well designed for, is efficient and elegant. In the second case you are using the stack to juggle input data as well as perform operations and hold intermediate results and that can cause a lot of grief, depending on the number of input variables and where in the equation they happen to be (re)used.
I find that a lot of stack manipulation and use of registers happens not because of the complexity of an equation, but because of the desire to move data around to put it into place for the equation. I think of those as unrelated problems.
Re: FourLevel RPN and the Real World  Manolo Sobrino  12132013 That's why some kind of formula evaluation capability makes a lot of sense. RPN makes single evaluation straightforward (and so much fun), but reusing the algebra means you have to write a program. That's fine if I have to perform the calculation 100 times, but what if I need it just twice? It isn't really costeffective... I always keep around a formula calculator for this. In an EOS calculator you'd just get back, edit the line and evaluate again. Keeping simple things simple has its beauty too.
