Very Very Ergent...



  • 1. using the Root function with Algebraic and RPL
    I am attempting to learn some of the finer but simple details of the HP50g. The calculator mode is set to rpn. I have created 2 objects: A << X X * 1 - >> according to the manual this is type 8 object in User RPL language and B ' X^2-1' according to the manual this is a type 9 algebraic object The numeric solver (item 4 under apps then item 1 solve equation) readily finds the 2 roots of -1 and 1 for both A and B. Then I used the graph function to graph A and B one at a time. First I deleted the X object created by the numeric solver. Both show the correct graph but the RPL example (graph A) has a difference. When I use the graph functions Root and Isect they cannnot find a root. The message constant? is displayed for both Root and Isect. The plot setup is set to function and the independent variable is set to X. Do I have another setting set incorrectly or is there a deeper meaning here? Any insight would be much appreciated. Randy
  • 2. Klotz Ram Card for 48gx
    Greetings! A few time ago I bought a Klotz Ram Card (4x128kb RAM for HP48) on ebay, directly from Oliver Klotz but I lost the instruction sheet telling how to intall / remove the ram card, since the card has 4 micro-switches for installing it on slot 1 or slot 2, write protection, etc. I've already tried to contact Oliver Klotz through ebay, but got no answer. Does anyone have those instructions?! Many thanks. Ernesto.
  • 3. SHA1?
    Is the SHA1 hash implemented for HP48/49/50? I found MD5, DES, ... But no SHA1 :( Robert Tiismus
  • 4. PC does not recognize HP48gii
    I did a search, but could not find an answer to my problem. Not that it isn't there somewhere! I have a refurbished HP48gii. And in using the Conn4X program the PC cannot find the calculator. Are there particular flag settings or other settings that need to be set for this to work properly? Note also that initially the company (a certified HP calc reseller) sent me a USB connector cable instead of the Serial connector cable. Thinking that maybe HP changed the PC connector cable type, I tried the USB connector cable anyhow. I now have the Serial connector cable and still no luck. Could using the USB connector cable have possibly damaged to calculator? Thank you for any help!

Very Very Ergent...

Postby yamahdiefatemeh » Wed, 17 Oct 2007 20:13:58 GMT

How can I solve dy/dx=(x^3+y^3)/(x^3-y^3)
Thanks a million...

Re: Very Very Ergent...

Postby sc_usenet » Thu, 18 Oct 2007 03:41:49 GMT

For implicit differentiation on a 50g, you need to tell it that y is a
function of x (otherwise it assumes that y is a constant). You can do
this by replacing y with Y(X) when entering the expression. Then use
DERVX (like any other derivative) and it gives you something with
d1Y(X) in it. Type in d1Y(X) and use SOLVE (not SOLVEVX because d1Y(X)
is [hopefully] not your system variable). It should return

d1Y(X) = Y(X)/X

In other words, dy/dx = y/x.

Note that in order to type in something like Y(X) you need to use
algebraic mode (i.e. the single quotes). Parenthesis are not valid
syntax in RPN.


Re: Very Very Ergent...

Postby rfellows » Thu, 18 Oct 2007 03:42:14 GMT

On my 48GX I just pull up the "Differentiate..." input form in the
"Symbolic" menu, input the above expression, select X (as the variable
of differentiation), make sure "Symbolic" is in the "Result" field,
and press OK.  What comes up is 3*X^2/(X^3-Y^3)-(X^3+Y^3)*(3*X^2)/(X^3-

I think the process is similar on the 49G+ and 50G.


Re: Very Very Ergent...

Postby Saturn rising » Thu, 18 Oct 2007 04:43:21 GMT


 > How can I solve dy/dx=(x^3+y^3)/(x^3-y^3)

What is that?  A differential equation?

"Solve this" is easier when one knows what it is ;-)


Re: Very Very Ergent...

Postby Virgil » Thu, 18 Oct 2007 05:47:17 GMT

If you mean "urgent", try


Re: Very Very Ergent...

Postby Michael » Thu, 18 Oct 2007 06:16:10 GMT

On the 35s? mwhhha

Mick C

Re: Very Very Ergent...

Postby ~kurt » Thu, 18 Oct 2007 10:20:24 GMT

Smells like someone's homework problem to me....

- Kurt

Re: Very Very Ergent...

Postby greenchile505 » Thu, 18 Oct 2007 11:49:46 GMT

"Very, Very ergent" [sic] smells like someone's TEST problem to me....

How flattering it is that students are Wifi-ing this group during
exams to request answers!


Re: Very Very Ergent...

Postby Scott Hemphill » Thu, 18 Oct 2007 12:29:02 GMT

 XXXX@XXXXX.COM  writes:

If I was looking for a closed form solution, I wouldn't do this on a
calculator.  Anyway, if you substitute y = u*x you can separate the
variables.  You wind up with dx/x on one side and something of the
form f(u)/g(u) du on the other.  All you have to do is integrate both
sides.  g(u) is a quartic.  Find its two quadratic factors and write
f(u)/g(u) as a sum of partial fractions.  Then you can integrate it.
It's a little messy.

Scott Hemphill	 XXXX@XXXXX.COM 
"This isn't flying.  This is falling, with style."  -- Buzz Lightyear

Re: Very Very Ergent...

Postby Virgil » Thu, 18 Oct 2007 13:24:39 GMT

In article < XXXX@XXXXX.COM >,

In fact, you can do it on an hp49 or hp50.

Even with a calculator to help it is more than a little messy.

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