1 ENTER 3 / 3 * 1 

01222016, 09:18 PM
Post: #1




1 ENTER 3 / 3 * 1 
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.


01222016, 09:26 PM
Post: #2




RE: 1 ENTER 3 / 3 * 1 
My old Sharp EL512 does the same, by giving 1. 11
HP11, HP41C, HP41CV, HP41CX, MATH/STAT, Surveying, X MEM, 82143A printer, 82104A card reader 

01222016, 09:33 PM
Post: #3




RE: 1 ENTER 3 / 3 * 1 
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:) 

01222016, 09:34 PM
Post: #4




RE: 1 ENTER 3 / 3 * 1 
Amazing! I thought that it was a peculiarity of HP calculators.


01222016, 09:44 PM
Post: #5




RE: 1 ENTER 3 / 3 * 1 
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. 

01222016, 10:08 PM
Post: #6




RE: 1 ENTER 3 / 3 * 1 
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 

01222016, 10:15 PM
Post: #7




RE: 1 ENTER 3 / 3 * 1 
Paul, I think that I get your meaning. HP is being transparent as to how a calculation is being done. Verswy interesting. Thank you!


01222016, 10:57 PM
Post: #8




RE: 1 ENTER 3 / 3 * 1 
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*31 is in your head. :P
David Brunell Houston, Texas 

01222016, 11:12 PM
Post: #9




RE: 1 ENTER 3 / 3 * 1 
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! 

01222016, 11:21 PM
Post: #10




RE: 1 ENTER 3 / 3 * 1 
My HP45, in default Fix 2 display mode, returns "0.00" :)


01222016, 11:31 PM
Post: #11




RE: 1 ENTER 3 / 3 * 1 
Interesting that it does that. Thanks!


01222016, 11:46 PM
Post: #12




RE: 1 ENTER 3 / 3 * 1   
01222016, 11:50 PM
Post: #13




RE: 1 ENTER 3 / 3 * 1   
01232016, 12:33 AM
Post: #14




RE: 1 ENTER 3 / 3 * 1 
HPs don't handle bleen correctly either.
2speed HP41CX,int2XMEM+ZEN, HPIL+DEVEL, HPIL+X/IO, I/R, 82143, 82163, 82162 25,35,45,55,65,67,70,80 

01232016, 02:34 AM
(This post was last modified: 01232016 02:35 AM by Paul Berger (Canada).)
Post: #15




RE: 1 ENTER 3 / 3 * 1 
(01222016 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 TI59 returns 1E12, my Commodore PR100 returns a similar result as does any HP calculator I have handy. 

01232016, 06:29 AM
Post: #16




RE: 1 ENTER 3 / 3 * 1 
OK, I'll play along. TI36X, 1E12. 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.
David Brunell Houston, Texas 

01232016, 06:35 AM
Post: #17




RE: 1 ENTER 3 / 3 * 1 
TI57: 1x10^(10)
HP11, HP41C, HP41CV, HP41CX, MATH/STAT, Surveying, X MEM, 82143A printer, 82104A card reader 

01232016, 07:10 AM
(This post was last modified: 01232016 09:41 AM by Paul Dale.)
Post: #18




RE: 1 ENTER 3 / 3 * 1   
01232016, 09:22 AM
Post: #19




RE: 1 ENTER 3 / 3 * 1 
1.E34
Free42 V1.5.5 (iPhone App) 

01232016, 09:48 AM
Post: #20




RE: 1 ENTER 3 / 3 * 1 
−1.00000000ᴇ−12
HP Prime (iPhone App) 

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