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+--- Thread: 1 ENTER 3 / 3 * 1 - (/thread-5575.html)
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1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 09:18 PM
I've always wondered why this kind of calculation on HP calculators returns a tiny negative residual, but this is not the case with other brands like TI, which return 0. I assume HP sees some advantage in doing arithmetic this way. Any help with this would be greatly appreciated.
RE: 1 ENTER 3 / 3 * 1 - - boniholmes - 01-22-2016 09:26 PM
My old Sharp EL-512 does the same, by giving -1. -11
RE: 1 ENTER 3 / 3 * 1 - - walter b - 01-22-2016 09:33 PM
1/3 = 0.333...3 (the number of digits depends on the respective calculator). Take this and multiply by 3 and you'll get 0.999...9 instead of 1. Subtracting 1 will result in -1 ULP, e.g. -1x10^(-16) on the WP 34S. So far, everything is perfectly ok on this calculator as well as on every HP calc I know.
Others will know more about TI.
d:-)
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 09:34 PM
Amazing! I thought that it was a peculiarity of HP calculators.
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 09:44 PM
Thanks Walter. I knew that it is deliberate and understand how it arises, but wondered why HP chooses to do it this way while TI doesn't. Maybe someone here will know.
On some TV show years ago, maybe Nova, they has some college math or science teacher showing his desk drawer filled with calculators that "failed" that test, but obviously there must be a good reason for HP's approach.
RE: 1 ENTER 3 / 3 * 1 - - Paul Dale - 01-22-2016 10:08 PM
HP calculators aren't lying to you about the result. The ones that give a perfect 1 are lying.
I don't trust calculators that lie.
- Pauli
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 10:15 PM
Paul, I think that I get your meaning. HP is being transparent as to how a calculation is being done. Verswy interesting. Thank you!
RE: 1 ENTER 3 / 3 * 1 - - quantalume - 01-22-2016 10:57 PM
Considering a lot of great engineering work was done with slide rules, I'll take 10 significant digits any day without complaint. The best way to work 1/3*3-1 is in your head. :-P
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 11:12 PM
No complaints here, David. However, I do wonder about HP's rationale.
Btw. I deeply regret having sold my Posft Versalog slide rule decades ago. What a beauty it was!
RE: 1 ENTER 3 / 3 * 1 - - BobVA - 01-22-2016 11:21 PM
My HP45, in default Fix 2 display mode, returns "-0.00" :-)
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 11:31 PM
Interesting that it does that. Thanks!
RE: 1 ENTER 3 / 3 * 1 - - Gerson W. Barbosa - 01-22-2016 11:46 PM
(01-22-2016 11:12 PM)hank Wrote: However, I do wonder about HP's rationale.
Some enlightenment here and here, by Rodger Rosenbaum.
RE: 1 ENTER 3 / 3 * 1 - - hank - 01-22-2016 11:50 PM
(01-22-2016 11:46 PM)Gerson W. Barbosa Wrote:(01-22-2016 11:12 PM)hank Wrote: However, I do wonder about HP's rationale.
Some enlightenment here and here, by Rodger Rosenbaum.
Thanks a lot Gerson. I'll check out the links.
Hank
RE: 1 ENTER 3 / 3 * 1 - - TASP - 01-23-2016 12:33 AM
HPs don't handle bleen correctly either.
RE: 1 ENTER 3 / 3 * 1 - - Paul Berger (Canada) - 01-23-2016 02:34 AM
(01-22-2016 09:18 PM)hank Wrote: I've always wondered why this kind of calculation on HP calculators returns a tiny negative residual, but this is not the case with other brands like TI, which return 0. I assume HP sees some advantage in doing arithmetic this way. Any help with this would be greatly appreciated.
Well not all TI calculators TI-59 returns -1E-12, my Commodore PR100 returns a similar result as does any HP calculator I have handy.
RE: 1 ENTER 3 / 3 * 1 - - quantalume - 01-23-2016 06:29 AM
OK, I'll play along. TI-36X, -1E-12. I have a lot of other TI calcs I could try, but this one is solar, whereas the others need batteries which I'm too lazy to round up.
RE: 1 ENTER 3 / 3 * 1 - - boniholmes - 01-23-2016 06:35 AM
TI-57: -1x10^(-10)
RE: 1 ENTER 3 / 3 * 1 - - Paul Dale - 01-23-2016 07:10 AM
For the Sinclair Scientific simulator: -1.0000-05
Pauli
RE: 1 ENTER 3 / 3 * 1 - - Steve Simpkin - 01-23-2016 09:22 AM
-1.E-34
Free42 V1.5.5 (iPhone App)
RE: 1 ENTER 3 / 3 * 1 - - Terje Vallestad - 01-23-2016 09:48 AM
−1.00000000ᴇ−12
HP Prime (iPhone App)