HP 20b logarithm error  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: HP 20b logarithm error (/thread145356.html) 
HP 20b logarithm error  Michael Andersson  01042009 I'm not sure whether this subject has been discussen on the forum befor or not, but when I try to calculate the logaritm of large numbers with my new 20b I get the wrong answers.
Some examples (correct answer in parenthesis):
1e16^.5=1e5 (1e8) < wrong answer Re: HP 20b logarithm error  Gerson W. Barbosa  01042009 Thanks for pointing this out. Errors involving logarithms used to occur only in nonHP calculators. See this old thread, Errors in Calculators. The QBASIC program below, based on Taylor series (see message #4 in the mentioned thread) is far from perfection but gives correct answers to your examples:
1 DEFDBL AL: DEFINT MN: DEFDBL OZ Gerson.
Re: HP 20b logarithm error  Thomas Klemm  01042009 Quote: cf. 20b and logs
Re: HP 20b logarithm error  Palmer O. Hanson, Jr.  01052009 Gerson:
You wrote Quote: But, the early HP35's had a bug such that 2.02 ln e^{x} was equal to 2 . Is there a discussion somewhere that tells whether the problem was in the ln calculation or in the e^{x} calculation?
Palmer
Re: HP 20b logarithm error  Karl Schneider  01052009 Michael  Please read the thread that Thomas Klemm linked. You will find that the commonlogarithm errors were present on an earlier firmware version, which, I would say, ought not to have been released for commercial sale. Each attendee of the HHC 2008 event in Corvallis received a new HP20b. Mine has a later serial number CNG83300019, and it does not exhibit the flaws that yours does. In my opinion, you're entitled to an exchange. Gross math errors like those are unacceptable.  KS
Re: HP 20b logarithm error  Gerson W. Barbosa  01052009 I had forgotten about the HP35 bug. Anyway, that one was readily corrected. Please take a look at http://www.hpmuseum.org/cgisys/cgiwrap/hpmuseum/archv015.cgi?read=89395
Gerson.
Re: HP 20b logarithm error  MikeO  01062009 Interesting. I, like Karl, got a 20b at the HHC2008 conference serial number CNG83300332  which does not exhibit the problem. I already had an older 20b  serial number CNG82800049. Which also does not exhibit the problem. This appears "older" than Michael's serial number of CNG82804713. Mike
Edited: 6 Jan 2009, 12:49 a.m.
Re: HP 20b logarithm error  David Hayden  01132009 Michael, can you post the exact key strokes you used to generate the error starting from factory default poweron conditions?
Re: HP 20b logarithm error  Gene Wright  01132009 50 e^x
display may not show 50 as it should.
Re: HP 20b logarithm error  Michael Andersson  01132009 Quote: An example: [1] [shift] [EEX] [5] [0] [shift] [Math] [up] [INPUT] Result: 32, correct answer 50.
I've tried to contact HP on the subject but have so far not recieved an answer.
Re: HP 20b logarithm error  Gene Wright  01132009 HP is aware of this bug.
Re: HP 20b logarithm error  Karl Schneider  01142009 Mike  As I stated above, you should get that unit exchanged.
 KS
Re: HP 20b logarithm error  Michael Andersson  01142009 I'm sure HP is aware of the problem. However, almost two weeks have gone since I contacted the support and I have not yet recieved an answer.
Re: HP 20b logarithm error  Don Shepherd  01142009 Michael, don't hold your breath. I contacted them twice, over 6 months ago, about an error in one of their web pages, and the error is still there.
