Post Reply 
For which models was 2^3>8?
04-04-2017, 07:18 PM (This post was last modified: 04-04-2017 07:19 PM by Dieter.)
Post: #11
RE: For which models was 2^3>8?
(04-04-2017 06:45 PM)james summers Wrote:  Thanks for the great explanation, Dieter.

Just playing around, my MK-61, after a slight pause gives 7.9999993.
Doing [2] [ENTER] [ln] [3] [x] [ex] also gives 7.9999993.

Interesting. Without guard digits it should be 7.9999973. What are the intermediate results you get for ln 2 and 3x this?

(04-04-2017 06:45 PM)james summers Wrote:  The 25C is more accurate, but similar, in that [2] [ENTER] [3] [yx] and [2] [ENTER] [ln] [3] [x] [ex] both give 8,000000002.

The 25 uses 10 digits as opposed to 8 in the MK-61.

(04-04-2017 06:45 PM)james summers Wrote:  However, my 32E, 41CV and 15C, whilst giving [2] [ENTER] [3] [yx] as 8.000000000, for [2] [ENTER] [ln] [3] [x] [ex] they give 8,000000003.

Why do you add an [ENTER] before the log? It's classic RPN. ;-)

The HP32/41/15 of course use the "new accuracy" since 1976 with three additional guard digits. That's why even with a manually calculated exponentional you get the correctly rounded value ...003. The difference to the HP25 result ...002 is probably due to different algorithms and/or rounding methods. In 1976 there were more improvements than just adding the guard digits, cf. the mentioned HP Journal article.

BTW, if you do not have access to the latter: most of the interesting stuff is available on hpl.hp.com.

Dieter
Find all posts by this user
Quote this message in a reply
Post Reply 


Messages In This Thread
For which models was 2^3>8? - Joe Horn - 04-04-2017, 05:03 AM
RE: For which models was 2^3>8? - Joe Horn - 04-04-2017, 12:17 PM
RE: For which models was 2^3>8? - pier4r - 04-04-2017, 05:20 PM
RE: For which models was 2^3>8? - Dieter - 04-04-2017, 05:51 PM
RE: For which models was 2^3>8? - pier4r - 04-04-2017, 06:10 PM
RE: For which models was 2^3>8? - bshoring - 04-04-2017, 06:16 PM
RE: For which models was 2^3>8? - teenix - 04-05-2017, 07:50 AM
RE: For which models was 2^3>8? - bshoring - 04-05-2017, 06:08 PM
RE: For which models was 2^3>8? - Dieter - 04-04-2017 07:18 PM
RE: For which models was 2^3>8? - Dieter - 04-04-2017, 07:53 PM
RE: For which models was 2^3>8? - bshoring - 04-04-2017, 10:14 PM
RE: For which models was 2^3>8? - Andres - 06-23-2020, 04:39 AM



User(s) browsing this thread: 1 Guest(s)