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+--- Thread: HP35S: a new 2*2 solve bug? (/thread-19470.html)
HP35S: a new 2*2 solve bug? - Roberto Volpi - 01-25-2023 08:05 AM
Hi all:
fighting with a simple 2*2 linear system with the help of our beloved HP35S I am observing a possible new bug.
I was trying to solve the following linear system of 2 unknowns:
s-t=0
-2s-3t=-20
Nothing hard to solve, and even a not so smart mathematician can guess that s=4 and t=4
But my HP35S, after inputing the data the usual way, states: NO SOLUTION.
Till yesterday it was working correctly, so I don't know where is the problem. Batteries are ok, changed in October last year, so just 3 months ago.
For your info, during these days I made lot of calculations involving vectors.
This calculator is really an inexhaustible source of surprises...
RE: HP35S: a new 2*2 solve bug? - BINUBALL - 01-25-2023 10:55 AM
There is thread discussing the problem. And also I can reproduce error with simulator.
Quote:It appears that registers G...L are used internally in the 2*2 lin. solve in an unusual way. If there is anything other than a real number in these registers (a complex number or a vector) the linear solver returns "no solution." Kind of interesting, as these registers are not overwritten after using the linear solver, which appears to indicate that these registers are not actually used.
https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv019.cgi?read=161919
RE: HP35S: a new 2*2 solve bug? - rawi - 01-25-2023 11:03 AM
I tried it as well.
After typing in the values for A to F (A=1., B=-1, C=0, D=-2, E=-3, F=-20) and pressing R/S my HP 35s shows:
X=4.0000 and after pressing arrow-down key: Y=4.0000
So everything is fine and I cannot see a bug.
RE: HP35S: a new 2*2 solve bug? - Roberto Volpi - 01-25-2023 11:09 AM
(01-25-2023 10:55 AM)BINUBALL Wrote: There is thread discussing the problem. And also I can reproduce error with simulator.
Quote:It appears that registers G...L are used internally in the 2*2 lin. solve in an unusual way. If there is anything other than a real number in these registers (a complex number or a vector) the linear solver returns "no solution." Kind of interesting, as these registers are not overwritten after using the linear solver, which appears to indicate that these registers are not actually used.
https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv019.cgi?read=161919
Thanks for your prompt reply.
After clearing variable registers, everything is now working fine.
It should be added to the article resuming the uptodated list of bugs for HP35S
RE: HP35S: a new 2*2 solve bug? - Massimo Gnerucci - 01-25-2023 04:09 PM
(01-25-2023 11:09 AM)Roberto Volpi Wrote: It should be added to the article resuming the uptodated list of bugs for HP35S
#18
RE: HP35S: a new 2*2 solve bug? - Maximilian Hohmann - 01-25-2023 04:31 PM
(01-25-2023 04:09 PM)Massimo Gnerucci Wrote: #18
and also #23 !
RE: HP35S: a new 2*2 solve bug? - Paul Dale - 01-25-2023 10:52 PM
(01-25-2023 04:31 PM)Maximilian Hohmann Wrote: and also #23 !
I must have been blind to miss the earlier entry. Latter one removed and the earlier one updated.
Pauli