Re: Bug in HP-35S?


HI, Joel:

Please have a look at my primary analysis of your interesting
bug, which I've
posted as a new thread at the MoHP Forum, here:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=126708#126708

Best regards.



On Oct 15, 8:33 pm, "Joel Koltner" <JKolstad71HatesS...@xxxxxxxxx>
wrote:
I've run the following program on a couple of HP-35S machines, and both of
them indicate that something Very Strange is happening in how equations are
being evaluated. Anyone else want to try this out?

Enter the following program:

LBL A
156.25
STO X
208.333333334 ;There are eight 'threes' in there
STO R
1.77951304201
STO Q
-R*X/(X*Q-R) ;Should evaluate to roughly -467, and it does
-R*X/(X*Q-R) ;Should (still) evaluate to roughly -467, but calculator
outputs 31.323 instead!
RTN

It's important that the program is entered exactly as shown. Note that the
"-" in the expressions are entered with the "+/-" (change sign) key, not the
"-" (subtract) key. Changing the numerical constants will (often) make the
expressions evalulate correctly. Some minor changes (e.g., changing -R to +R)
in the expressions still demonstrates the error, but making significant
changes (such as changing X*Q-R to just X*Q) no longer does. Changing the
expressions to R*-X/(X*Q-R) fixes the problem. Removing the initial "-" in
the first expression causes the second expression to fail, although the output
is then -52.287 rather than 31.323!

I discovered this while creating a real program, which is rather alarming...!
Anyone have any ideas? Is this a well-known bug somehow?

Thanks,
---Joel


.

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