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HP Forum Archive 14

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28S Programming
Message #1 Posted by John Morast on 8 Apr 2004, 7:23 p.m.

I have a question on programming my HP 28S. I am following the procedure in the owners manual, but upon solving the equation, the wrong answer is provided. The equation I am solving is a fluid flow problem:

Q = 1.49/n * A * R^2/3 * S^1/2

HP no longer offers support for the 28S. I am taking the PE exam and they outlawed the 48GX, so I'm dusting off my 28S. Anyone aware of another method of programming or previous issues with programming the 28S? Thanks!

      
Re: 28S Programming
Message #2 Posted by J. Lopez on 8 Apr 2004, 8:02 p.m.,
in response to message #1 by John Morast

In the 28S's operator hierarchy rules, raising to a power is done before division/multiplication; so, 'R^2/3' is different from 'R^(2/3)'. Also, without parenthesis in the equation, your last term becomes 'S/2' instead of 'SQRT(S)', which is probably what you intended. Hope this helps.

            
Re: 28S Programming
Message #3 Posted by J Morast on 9 Apr 2004, 2:41 p.m.,
in response to message #2 by J. Lopez

I thought I'd tried that in my many iterations of equation input. I will double check. Thanks.

      
Re: 28S and the NCEES - can it be used?
Message #4 Posted by Randy Sloyer on 8 Apr 2004, 8:42 p.m.,
in response to message #1 by John Morast

I would not be surprised to hear the NCEES banned the 28 series as well for it has alpha editing ability and IR transmission, two very big no-no's.

Has anyone out there been able to use a 28?

      
Re: 28S Programming
Message #5 Posted by Norris on 8 Apr 2004, 9:05 p.m.,
in response to message #1 by John Morast

This question has come up in other forums, like the PE exam forum at ppi2pass.com. It is widely assumed that the 28 series is implicitly *banned* under current NCEES rules.

It's true that the 28 is not explicitly listed on the NCEES "banned" list (which includes the 41, 42, 48, and 49). But NCEES has never claimed that this list is all-inclusive. In fact, NCEES has banned *any* calculator that meets the following general description:

"Of great concern is the ability to type in text, store it in memory, and then communicate via wireless or cable connections to another calculator, personal computer, printer, or other electronic device. If a calculator model can be made to communicate through the use of modules, software, and/or other add-on devices, then this calculator is deemed to possess communication capabilities and will be prohibited."

The 28S can clearly do these things, so it appears to be unacceptable under the current NCEES rules.

The new NCEES calculator policy takes effect with the April 2004 exams, which will not occur until April 16-17. So no one has "tested" the ban with a 28S yet. In practice, enforcement of the policy will be up to the exam proctors, who may or may not be able to recognize the features of the 28S. It's entirely possible that some proctors would disallow it and that others would let it pass. However, the 28S appears to be technically illegal in either case.

In the future NCEES may ban all calculators except for those on a relatively short "approved" list, in order to simplify enforcement of the policy. The only RPN calculators that NCEES has explicitly "approved" to date are the HP 32 and 33 series.

      
28S on PE exam?? No way !!
Message #6 Posted by Driscoll on 8 Apr 2004, 10:41 p.m.,
in response to message #1 by John Morast

Time for a reality check. You plan to take a device with an alpha keyboard and a wireless transmitter into an NCEES exam? Why do you think the 48GX was banned?

      
Re: 28S Programming
Message #7 Posted by Vieira, Luiz C. (Brazil) on 10 Apr 2004, 1:05 a.m.,
in response to message #1 by John Morast

Hi;

the HP28S (and all RPL calculators) identify an "expression" (a general term for any equation) when it's surounded by [']. As you were able to use the SOLVER and got a wrong answer, I'd ask you, please, to try this one:

'Q=1.49/n*A*R^(2/3)*S^(.5)'
The "S^(.5)" may also be written as S^.5 or you can type the square-root ([SHIFT][-]) and S; either of each will work fine.

I am not sure about what you see after typing the equation in and pressing [ENTER], but if you get no error and all variables appear as menu labels when you activate the SOLVER (i.e.: [Q][N][A][R][S][LEFT=]), then there is something alse missing.

Is it possible to go further, now?

Success.

Luiz (Brazil)

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