Brand new to RPN, few questions on bits!

[Kyburo]

Hi,

I'm brand new to this forum and RPN in general.

I'm just about to start (in the next few weeks) studying Mechanical engineering at uni and just stumbled across RPN last week.

Long story short is I've the casio 2013 fx991es+ but always thought it seemed fairly unsturdy and never liked it all that much.

In my searching I've found (a) that there are a ton of features for this casio I wasn't told about by previous teachers, most likely to stop me using it when learning new maths and (b) There is a different type of calculator out there which seemed kind of cool, the RPN calc.

Since then I've realised my mac osx calculator has a built in RPN mode, found some free HP48 apps on my android device tablet and also then happily discovered this forum and the WP34S software that I'm using to test out my RPN understanding on.

Well, that was much more long than short. Apologies! On to my few questions.

-------------

First question: A cool new feature I found on my casio is that I can enter in an equation including variables like x, and then at the end give the x value and let it perform the calculation.

eg) x^2 + 6x + 9
then after entering the above I can use "calc" to specify that x = 2 say, and it'll spit out the answer to the above equation.

I've been trying to find a simple explanation to do this on a RPN calc, but not found anything so far, and the manuals for both the HP35s and WP34s are a bit of info overload right now.

*Solved*
Second question: Same setup as above, but instead using
x^2 + 6x + 9 = 0
And looking for a calculator to "solve" this for me, giving the x value (of x=-3)

Third question: An introduction on how to perform definite integration/differentiation, which again is something I've always done by hand, but have recently started testing my casio to see just how much stuff it can do for speed.

-------------

So let me apologise again, it's a bit cheeky of me to just turn up and drop a load of questions on this forum.. But I'm pretty keen to learn RPN as best I can before starting uni in a little over 2 weeks time, and I've a HP35s coming in the post on Monday so until then I'm mashing away at the WP34s with examples and bits

Basically looking for an alternative to the casio, even if I end up using both in tandem, I'm pretty convinced that getting my head fully around RPN is going to help my maths rather than hinder.

Also, hello!

Edit: I did find this link (http://h20331.www2.hp.com/Hpsub/download...ration.pdf) but have yet to get my hands on the HP35s, but with slightly different keys to the WP34s I wasn't sure where to start with this.

Edit2: Basically this style , but I'm not sure how you'd do the same on the WP34s (http://h20566.www2.hp.com/portal/site/hp....199480143) - Back to the WP34 manual

[Kyburo]

Hi Walter,

Thanks for the welcome

Unfortunately I'm limited to certain calculators for my course and it's exams.

Luckily the HP35s is one on the University approved list (so with any luck my deptartment also permits it) but I'd be unable to use the WP34s. Which really, seems a bit of a shame, I'm pretty surprised to find such a forum and following behind calculators, to the point where your custom emulating software works on every operating system (which works and looks great, especially as actual manufactorers like HP and Casio are windows only) and you can even purchase pre-made community improved calculators!

Hopefully the postman will deliver my HP35s on Monday, so I'll have the manual ready to start testing bits out.

Cheers
Kyle

[Thomas Radtke]

(09-06-2014 06:52 PM)Kyburo Wrote:  First question: A cool new feature I found on my casio is that I can enter in an equation including variables like x, and then at the end give the x value and let it perform the calculation.

eg) x^2 + 6x + 9
then after entering the above I can use "calc" to specify that x = 2 say, and it'll spit out the answer to the above equation.

Since you mentioned the 35s: Enter an equation into the equation editor. Pressing Enter or XEQ(*) on viewing this equation causes the calculator to request a value for x and subsequently calculates the result.

(*) XEQ is special as it conveniently evaluates equations also. Please have a look at the 35s manual which is available online - http://www.hp.com/ctg/Manual/c01579350.pdf

[Jeff_Kearns]

(09-06-2014 06:52 PM)Kyburo Wrote:  First question: A cool new feature I found on my casio is that I can enter in an equation including variables like x, and then at the end give the x value and let it perform the calculation.

eg) x^2 + 6x + 9
then after entering the above I can use "calc" to specify that x = 2 say, and it'll spit out the answer to the above equation.

I've been trying to find a simple explanation to do this on a RPN calc, but not found anything so far, and the manuals for both the HP35s and WP34s are a bit of info overload right now.

*Solved*
Second question: Same setup as above, but instead using
x^2 + 6x + 9 = 0
And looking for a calculator to "solve" this for me, giving the x value (of x=-3)

Third question: An introduction on how to perform definite integration/differentiation, which again is something I've always done by hand, but have recently started testing my casio to see just how much stuff it can do for speed.

Here is an excellent article written by Karl Schneider called "SOLVE and INTEG on HP's RPN-based models", that also covers the HP-35s.

Welcome to the forum.

Jeff Kearns

[Les Bell]

(09-06-2014 06:52 PM)Kyburo Wrote:  First question: A cool new feature I found on my casio is that I can enter in an equation including variables like x, and then at the end give the x value and let it perform the calculation.

eg) x^2 + 6x + 9
then after entering the above I can use "calc" to specify that x = 2 say, and it'll spit out the answer to the above equation.

I've been trying to find a simple explanation to do this on a RPN calc, but not found anything so far, and the manuals for both the HP35s and WP34s are a bit of info overload right now.

Good question! Of course, with modern calculators there are lots of ways to do this, but since you're specifically asking about RPN, I'll give you the way an old-school RPN purist would approach this, ever since the introduction of the HP-65 back in 1973: write a program.

Something like this:

Code:


LBL E     // Program runs when you press "E" or "XEQ E"
ENTER^    // Copy the value on the stack
x^2       // Square it
x<>y      // Get the other copy
6         // Multiply it by six
*
+         // x^2 + 6x
9         // Add 9
+
RTN       // End of program/subroutine

Now, whenever you want to evaluate that expression (it's technically not an equation), you just put the x value in the X register and press "E"; the little program runs, and you get the value of the expression left in the X register. You can also use this as a subroutine in other programs, e.g. to produce a table of values or even graph the expression.

For a lot of (repetitive) tasks, a short program is an easy solution - and this was probably the most common application of early programmable calculators like the HP-65, -55, etc.

[Kyburo]

Thanks for the tips so far, I'm a little over half way through the manual trying to get my head around taking their examples and modifying it for something similar to a question I'd normally have received.

Figured out bits like programming a recurring sequence of say Un+2 = (Un+1)^2 - 9Un

Although to perform this, I've had to program along the following lines, using V to represent Un+1, and U to represent Un:
U=2
V=5

EQN or RPN the above expression [post equals sign (this time it's an expression also right? since I've an equals sign, but its to explain it's a sequence rather than having a value defined on both sides?)]

(EQN) V^2 - 9xU
STO V
x<>y
STO U
x<>y
RTN

U=5
V=7

Not sure if there is a simpler way of copying the results into the various registers (or if that even makes sense for anyone to follow!)

Anywho, I'll finish going through the manual before asking any more questions, and also go through the guide linked by Jeff.

Also cheers Les! I can completely follow your programs logic thanks to the comments, and I'd not actually realised you could use ENTER^ in that way. Until now I've been using the STO feature at the start each time

[ndzied1]

Here is a handy reference for the 35s

http://h20331.www2.hp.com/Hpsub/cache/53...5-121.html

(If this link doesn't work then google: hp 35s learning modules and you should be able to find it. HP seems to change links often).

[Les Bell]

(09-09-2014 02:32 PM)Kyburo Wrote:  Also cheers Les! I can completely follow your programs logic thanks to the comments, and I'd not actually realised you could use ENTER^ in that way. Until now I've been using the STO feature at the start each time

OBTW, writing a short program that way is the standard way of defining a function for use with the solvers and root finders of the older RPN calculators. For example, with the HP-41CX and its Advantage Pac, one would store that program (albeit with a longer, global, label like "EX" rather than just "E"), then store the name of the function ("EX") in the calculator's alpha register, the initial search range into the y and x registers, then "XEQ SOLVE". With your example, and a starting range of (-5,5) it produces the answer of -3.0 in a few seconds. So that's the answer to your second question - again, from a old-style "classic RPN" point of view.