Talk:Difference engine

message: I don't have a written source, but a senior docent working at the Mountain View Computer History Museum said today that Nathan Myhrvold is extending his loan of the DE2 again (to the end of 2010). Should I change the article now, or wait for the museum to update its site? Seijihyouronka (talk) 04:28, 10 January 2010 (UTC)
thread_title:  Additional extension for the display of DE2 

message: The example of the polynomial is not correct. It states: 'A difference engine only needs to be able to subtract'. Though, the Difference Engine could only add. What's wrong is that the differences in the second column (column of 1st difference) are not subtracted correctly and need a minus sign. SvenPB 19:24, 6 August 2005 (UTC)
replies: text: That is not correct.  It is possible to produce appropriate polynomial approximations for any portion of the domain of the sine functions.  However, a single approximation will not be suitable for the entire domain.  That is true for many other transcendental functions as well, including logarithms.  This was well-known in Babbage's time; even with the Difference Engine it still would have been necessary for mathematicians to derive the appropriate polynomial approximations for various portions of the domain, and use each polynomial for only a portion of the tables being generated.  --Brouhaha (talk) 20:01, 12 May 2008 (UTC)
replies: text: That is exactly the same. As the second difference of a simple x^2 is a constant being 2, this function can be calculated without error. For trancendental functions, you'll not find such a beautiful constant and you're dependent on the number of columns: the lesser columns the sooner major deviations occur. Then you'll have to recalculate your differences and reprogram the column to expand your domain. Reprogramming needs human intervention and is a manual job.  SvenPB (talk) 14:12, 11 January 2009 (UTC)

text: Yes ok, but the mechanism is an adder and the subtraction is a trick. Then you're not using 9's complement, but 10's. Which is in fact 9's complement plus 1 (e.g. -0029 = 9970 + 0001 = 9971). Finaly, there's no mechanism in the difference engine to convert negative numbers to something readable. If printed, the difference engine would print 9971 instead of -(0028 + 0001) = 0029 SvenPB (talk) 14:52, 11 January 2009 (UTC)
thread_title:  Adding and subtracting? 

message: This 'method of differences' looks a bit like differential calculus to me. Is that wrong? E.g.: the first column is the function; the 2nd is the 1st derivative, and the 3rd is the 2nd derivative. Note that the third column of a 2nd-degree polynomial is constant, like the 2nd derivative. --Taejo 12:52, 27 August 2005 (UTC)
replies: text: The "method of differences" uses difference equations; "differential calculus" uses differential equations. They are very similar, except the first uses finite steps and the second infinitesimal steps. -- RTC 20:07, 7 September 2005 (UTC)
thread_title:  Method of differences? 

message: I'm not a computer science major, an engineer or anything of that sort, but this article seems terribly incomplete to me. There's no historical information (when was it designed, why wasn't it built), there's no discussion of the engineering principles. Cansomeone please work on this?
Zaklog 03:01, 12 February 2006 (UTC)
thread_title:  Historical information? 

message: im doing a power point on this topic i was wondering if anyone could plz add the history of the people's live's involved with the machine? thnx
-- Be BOLD. :-)
::Ha ha. I have an assignment due, I was wondering if anyone could plz do it for me? Thnx --Be EXCELLENT coz I need an A to pass.154.5.40.122 (talk) 13:16, 10 December 2011 (UTC)
thread_title:  student 

message: http://www.computerweekly.com/Articles/2008/03/31/230058/babbages-vintage-supercomputer-heads-to-us.htm
http://www.electronicsweekly.com/Articles/2008/04/01/43442/babbages-difference-engine-heads-for-california.htm
http://www.wired.com/gadgets/miscellaneous/multimedia/2008/04/gallery_babbage
Conrad T. Pino (talk) 02:51, 10 April 2008 (UTC)
replies: text: Nice to see someone reads us. --Petri Krohn (talk) 19:20, 11 January 2009 (UTC)
thread_title:  Now there are two 

message: Is there any documented evidence of the notion that the errors found in Babbage's plans were intentional mistakes--a sort of insurance against patent theft?  And if so, should the article reflect that in its coverage of the errors?  I've heard this idea from many a good mind, but no one has offered evidence. O0drogue0o (talk) 09:38, 17 September 2008 (UTC)
thread_title: Intentional Error

message: I have removed the folowing section from the article and restored my original text in section Difference engine#Initial values. I have done this for two reasons:
# This is not encyclopedic, it tryes to "demonstrate these concepts" through the use of examples.
# I do not understand any of it.
-- Petri Krohn (talk) 20:50, 11 January 2009 (UTC)
thread_title:  Pipeline Method 

message: I have a set of photos that I would be happy to contribute to the article if people would like to add them. The set is here: http://www.flickr.com/photos/0x0000org/sets/72157605376240530/
The photos are of the Difference Engine No. 2 exhibit at the Computer History Museum.  —Preceding unsigned comment added by Wikiwikimoore (talk • contribs) 23:57, 17 January 2009 (UTC)
thread_title: Photos from of version 2 from computer history

message: I don't understand this paragraph. The polynomials for the functions that Babbage was planning to use were perfectly known in his time. The paragraph is talking about statistical correlation or something. SvenPB (talk) 11:39, 6 February 2009 (UTC)
replies: text: No. -- Petri Krohn (talk) 14:25, 7 May 2009 (UTC)
thread_title:  Curve fitting 

message: The column headers in the table are incorrect.  p(x) for x=0 is indeed 2.00 but p(x+1) is 1.00 (i.e., 2^2 - 3 + 2).  The column headers should instead read p(x+0.1) not p(x+1). 
Ross Fraser (talk) 22:40, 5 April 2009 (UTC)
thread_title:  Method of Differences Table Incorrect 

message: The sentence:
Functions that are not polynomial functions but are infinitely differentiable can be expressed as power series, for example as a Taylor series.
is wrong as an example of function e-1/x2 fox x> 0 and 0 for x <= 0 shows.  —Preceding unsigned comment added by 4.143.95.100 (talk) 12:10, 14 June 2009 (UTC)
thread_title:  Incorrect claim 

message: Look at a Holtzapffel lathe and the high precision work possible with one. Late 18th (first lathe sold by the company June 31st, 1795) and 19th century equipment was capable of very precise tolerances. It was mostly a lack of funding and inability to envision what the thing would be useful for by those in positions to provide the funding, which prevented Babbage from getting his engines built. Bizzybody (talk) 05:57, 30 August 2010 (UTC)
thread_title:  Manufacturing tolerances. 

message: I'd be very curious to see some performance and timing data. Thanks! --Brian Fenton (talk) 21:12, 16 October 2010 (UTC)
thread_title:  Performance? 

message: All polynomials of finite order "converge" so I don't really understand to what the caption of the first photo is referring when it uses the phrase "converging polynomials." Is there some specific technical meaning that the author of this caption intended or is it merely pedantry? Shall I delete the word "converging?"154.5.40.122 (talk) 06:42, 4 December 2011 (UTC)
thread_title:  Converging polynomials 

message: In the table:  p(x) = 2x^2 − 3x + 2  when x=2,  P(2)=4  not 12920
88.104.128.60 (talk) 14:44, 4 April 2012 (UTC)
replies: text: I am wondering as well Harrmas (talk) 18:14, 27 March 2023 (UTC)
thread_title:  Method of differences 

message: Maybe worth noting in the article:
http://acarol.woz.org/difference_engine.html
I think it's hilarious...  — Preceding unsigned comment added by 84.135.18.129 (talk) 15:59, 17 May 2014 (UTC)
thread_title:  May be worth noting as a weblink 

message: Hello. I am not a Wikipedia editor. I am however a professional teacher who came to find out what the Difference Engine is. The introduction to the article is written to a level more suited to the preamble to a PhD dissertation. I haven't the faintest idea what it means. I came here looking for knowledge and you guys simply can't keep your big words in your pants for even an introduction. Congratulations - you understand it. The people you supposedly wrote it for haven't got a clue.... Please sort this out before you disappear up your own internal affairs. Off to consult Britannica. THIS IS AN ENCYLOPEDIA for people to learn from, not for you to show how clever you are!!!!
As no reply was given to this very serious request i am afraid that I decided to vandalise the article for which I apologise. The vandalism took the form of the following paragraph placed at the beginning of the article:
"This first paragraph is an anonymous and deliberate "vandalisation". The following article is incomprehensible to users of Wikipedia who do not have exceedingly high levels of Mathematical Knowledge on which to build further learning. Despite a request on the Talk Page for months, no reply has been received and no work done to resolve this matter. The author of this regrettable vandalisation notwithstanding requests that there be at least an introduction to this article that explains in plain English what the purposes and functions of the Difference Engine are so that the Wikipedia user can continue deeper into the article with some sort of awareness of the system and its purposes. The author regrets the vandalism."  — Preceding unsigned comment added by 217.44.205.7 (talk) 08:12, 20 July 2015 (UTC)
thread_title:  Please make this article inclusive 

message: I'm arranging a visit to photograph the Difference Engine at Intellectual Ventures in Bellevue, Washington in conjunction with Wikinews. Does anyone have specific parts of the machine I should try to photograph, particularity those we haven't seen or are not normally visible to the public? --Dennis Bratland (talk) 23:09, 15 February 2016 (UTC)
thread_title:  Photo requests of the Difference Engine 

message: *Video of Martin Wibergs difference engine
--89.25.210.104 (talk) 01:25, 16 February 2018 (UTC)
thread_title:  External links video proposition 

message: Why Difference engine, but Analytical Engine? Smeagol 17 (talk) 19:04, 6 November 2019 (UTC)
thread_title: Title spelling

message: The photo used in the box is really badly "photoshopped", presumably to clone out people's faces for privacy or whatever reason. Looks pretty bad in the article, it is visually distracting and the edit obscures parts of the exhibit. I suggest replacing it with a  one from Commons (if the license permits, I think it should so), or a newer one if available. Technicality nitpicker (talk) 16:50, 15 January 2023 (UTC)
thread_title:  Suggest to replace photo with clean, unedited one