Mike Sebastian's Calculator Forensics  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: Mike Sebastian's Calculator Forensics (/thread179826.html) 
Mike Sebastian's Calculator Forensics  Joerg Woerner  03082011 Hi Folks, There is still room for improvement  THIS $15.95 calculator checked out with 18 (!) digits of resolution and reported an unparalleled result of:
Cheers,
Joerg
Re: Mike Sebastian's Calculator Forensics  John B. Smitherman  03082011 Wow! Does it glow in the dark? ;)
Re: Mike Sebastian's Calculator Forensics  Joerg Woerner  03082011 No, but in the US you'll see only this bright lime green. In UK they have wonderful teal and pink versions, too. All made of recycled photocopiers and antibacterial keyboards ;))
Regards, It think it's useful  Frank Boehm (Germany)  03082011 when doing your time travel calculations and including the expansion of the universe with appropriate accuracy to not miss the bus. Re: Mike Sebastian's Calculator Forensics  Marcus von Cube, Germany  03082011 Hi Jörg, can you let it calculate tan 89.999999 degrees? There is a recent discussion about trig precision near discontinuities which revealed some astonishing results.
Re: Mike Sebastian's Calculator Forensics  Joerg Woerner  03082011 tan (89.999999) = 57295779.51... like my TI36X on the desk, too.
Rgeards, Re: Mike Sebastian's Calculator Forensics  Marcus von Cube, Germany  03082011 Thanks Jörg! What do you get if you subtract the integer part?
Re: Mike Sebastian's Calculator Forensics  Joerg Woerner  03082011 57295779.5130823151 on the Canon and 57295779.5132 on the TI36X
Joerg
Re: Mike Sebastian's Calculator Forensics  Marcus von Cube, Germany  03082011 The Canon is extremely accurate. The result is correctly rounded to the last digit. (The last digit should be a 0 and the following a 5. Taking rounding into account, the result is perfect.)
Re: Mike Sebastian's Calculator Forensics  Paul Dale  03092011 The 34s only gets 10 zeros after the decimal:
9.000000000029361 This is, however, the correctly rounded result for devices with sixteen digits. I.e. each operation correctly rounded its answer.
Re: Mike Sebastian's Calculator Forensics  Marcus von Cube, Germany  03092011 Pauli, that's the point. The forensics is not meant to highlight the accuracy of a certain calculator but to identify identical algorithms and/or calculator chips.
Re: Mike Sebastian's Calculator Forensics  Walter B  03092011
Quote:True for this level of precision we're talking about here. In general, however, the forensics sheds some light on the reliability of calculation results. Think of error propagation in iterative computations ... Re: Mike Sebastian's Calculator Forensics  Gerson W. Barbosa  03092011 Paul, The WP34s displays 9.00000000003, that is, the internal result is rounded to the number of digits of the display. HP used to round the result and truncate it to the number of digits in the display at the end of each operation. Thus, the HP42S displays 8.99999864267. HP's method makes sense because the results of the operations are coherent to the actual figures of the operands the user has access to (by examining their mantissas, for instance). I assume the 34s is a 16digit device, but the calculations are carried out with extra guard digits, otherwise it wouldn't achieve the correct rounded 16digit result we see. Another reason to get the WP34s as soon it's available :) Correct result for various numbers of digits in this old thread. Regards,
Re: Mike Sebastian's Calculator Forensics  Marcus von Cube, Germany  03092011 Gerson, wp34s *is* on the agenda. :)
Re: Mike Sebastian's Calculator Forensics  Paul Dale  03102011 Try subtracting 9 from that result :) Yes, the 34s is a 16 digit device. Registers are IEEE 854 64 bit packed decimals. As you guessed, internal calculations are in higher precision using unpacked decimal numbers. I could round to the display size (12 digits) easily enough. For a variety of reason I didn't.  Pauli
Edited: 10 Mar 2011, 1:34 a.m.
Re: Mike Sebastian's Calculator Forensics  Gerson W. Barbosa  03102011 Quote: Not necessary. I just pressed 'F' to see the full stack to 16 digits.
Quote: I'm glad you didn't. Regards,
Gerson.
