User talk:Jitse Niesen/Archive11

Warning:Javascript security issue

Hi! I need to inform you that I've protected Wikipedia:WikiProject User scripts/Scripts/Get Page Name because it allows users to add code to the javascript of other users. If you are an admin, you are still able to edit it, but if you are not an admin, please copy and paste it into your userspace to continue modifying it. We can set up a message at the old javascript page telling users to change their links. If you need help, please contact me or User:Eagle_101. Thanks, --uǝʌǝsʎʇɹnoɟʇs 01:02, 22 October 2007 (UTC)

Refactor block?

Could you make your block of IMNTU (talk · contribs) indefinite? It's obviously a vandalism only account. At Wikipedia talk:WikiProject Physics people are concerned that this editor will return to cause further disruption. Thanks. - Jehochman ^Talk 21:54, 30 October 2007 (UTC)

I do not often block accounts and thus I'm very cautious. But I see that you have more experience with blocks, and WP:BLOCK says that vandalism-only accounts can be blocked indefinitely, so I took up your suggestion. Cheers, Jitse Niesen (talk) 11:10, 31 October 2007 (UTC)

Melbourne Meetup

	Melbourne Meetup Next: Wikipedia:Meetup/Melbourne/46 - Tuesday 13 August, 2024 (watch) Last: 18 February 2023
See also: Australian events listed at Wikimedia.org.au (or on Facebook)

Hello! The Melburnians are having another meet-up! Please consult this page if you are interested to participate in the discussion! Thanks! Phgao 03:26, 2 November 2007 (UTC)

Runge-Kutta (RK4) method

Hi Jitse,

I saw some edits earlier today on the Runge-Kutta page. The earlier edits were from an IP address removing h factors from the $k_{i}$ terms. Being intrigued by edits like this from an IP source I checked back against my desk copy of Numerical Recipies but found a match to the restated equations. Nonetheless I decided to watch the page.

This evening I saw the reversion you subsequently made to the page. I've checked back against a second source, my trusty (but dusty), A&S, which has fourth order Runge-Kutta formulae on page 896 (eqns: 25.5.10 / 25.5.11) - with 25.5.10 being relevant. A&S is missing the h terms recently re-inserted. Specifically it gives these expressions:

${\begin{matrix}y_{n+1}=y_{n}+{\frac {1}{6}}k_{1}+{\frac {1}{3}}k_{2}+{\frac {1}{3}}k_{3}+{\frac {1}{6}}k_{4}+O\left({h^{5}}\right)\\[0.5em]k_{1}=hf\left(x_{n},y_{n}\right)\\[0.5em]k_{2}=hf\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}k_{1}\right)\\[0.5em]k_{3}=hf\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}k_{2}\right)\\[0.5em]k_{4}=hf\left(x_{n}+h,y_{n}+k_{3}\right)\\[0.5em]\end{matrix}}$

Numerical Recipies does cite A&S as it's primary source for equations so looking elsewhere Mathworld, here, is also consistent with the above (absenting h terms in the second function dimension.) In contrast following the links given on the article page I can see documents that do give formulas including the second h.

If possible would you be able to reconsider what the appropriate equations should be (I believe the h should be absent from the second dimension term inside the function, f) but perhaps the statement just needs the correct context.

I've left the article untouched and would welcome your thoughts before modifying these equations.

Very open to be corrected on any or all of the above.

Regards,

Asperal 21:23, 6 November 2007 (UTC)

Hi Asperal, and thanks for your polite message. It's almost too polite :) I'll have to keep it brief right now (and I have no time to check any books) but hopefully I'll find time to come back to it tomorrow. Firstly, my last edit summary on that page was quite improper. The edit was technically incorrect because it left out one of the factors of h, but it was clear what it meant to say, namely the formulation that you wrote above.

To come to the real matter: there are two ways to formulate the RK4 method. One is as you write above, the second one is the one in the article:

${\begin{matrix}y_{n+1}=y_{n}+{\frac {1}{6}}hk_{1}+{\frac {1}{3}}hk_{2}+{\frac {1}{3}}hk_{3}+{\frac {1}{6}}hk_{4}+O\left({h^{5}}\right)\\[0.5em]k_{1}=f\left(x_{n},y_{n}\right)\\[0.5em]k_{2}=f\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}hk_{1}\right)\\[0.5em]k_{3}=f\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}hk_{2}\right)\\[0.5em]k_{4}=f\left(x_{n}+h,y_{n}+hk_{3}\right)\\[0.5em]\end{matrix}}$

Depending on your background (which I don't know), it may be obvious to you that these are the same or it may not. In the latter case, I'll be glad to explain it further.

Both formulations are used in the literature, so we have to pick one and use that one. I admit that it could be explained better and probably we should explain in the article that both formulations exist, but just changing from one formulation to the other is not a solution. To be honest, I think the article Runge–Kutta methods needs a thorough rewrite, and one of the things that should be tackled is to clear up this confusion.

As I said, this is just a quick reaction and probably not the final word on the matter. Please let me know what you think. -- Jitse Niesen (talk) 00:16, 7 November 2007 (UTC)

Good morning and thanks for the swift reply. I can follow directly the first step going from the equations I presented to the following:

${\begin{matrix}y_{n+1}=y_{n}+{\frac {1}{6}}hk_{1}+{\frac {1}{3}}hk_{2}+{\frac {1}{3}}hk_{3}+{\frac {1}{6}}hk_{4}+O\left({h^{5}}\right)\\[0.5em]k_{1}=f\left(x_{n},y_{n}\right)\\[0.5em]k_{2}=f\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}k_{1}\right)\\[0.5em]k_{3}=f\left(x_{n}+{\frac {1}{2}}h,y_{n}+{\frac {1}{2}}k_{2}\right)\\[0.5em]k_{4}=f\left(x_{n}+h,y_{n}+k_{3}\right)\\[0.5em]\end{matrix}}$

and then on to rewriting the first element (for implementation) as:

$y_{n+1}=y_{n}+{\frac {1}{6}}h\left(k_{1}+2k_{2}+2k_{3}+k_{4}\right)+O\left({h^{5}}\right)$

I'll reread the article closely and see if I can work out the last step. As mentioned before I suspect this will be in the exact definition of the problem rather than the final statements.

Asperal 08:06, 7 November 2007 (UTC)

If I may suggest, whichever set of equations is used, the LaTeX markup should use the align environment:

${\begin{aligned}y_{n+1}&=y_{n}+{\tfrac {1}{6}}hk_{1}+{\tfrac {1}{3}}hk_{2}+{\tfrac {1}{3}}hk_{3}+{\tfrac {1}{6}}hk_{4}+O\left({h^{5}}\right)\\k_{1}&=f\left(x_{n},y_{n}\right)\\k_{2}&=f\left(x_{n}+{\tfrac {1}{2}}h,y_{n}+{\tfrac {1}{2}}k_{1}\right)\\k_{3}&=f\left(x_{n}+{\tfrac {1}{2}}h,y_{n}+{\tfrac {1}{2}}k_{2}\right)\\k_{4}&=f\left(x_{n}+h,y_{n}+k_{3}\right)\\\end{aligned}}$

It is more standard, and easier to read. --KSmrq^T 17:16, 7 November 2007 (UTC)

Got it. As always it seems obvious (but especially so in this case since it is so direct) once the logic is followed. Thanks again for your time, and the polite replies.

KSmrq also thanks for the LaTex suggestion - I am slowly learning the parser functions. Although it will make no difference to the output display of the article, at least on my screen, I'm going to add this in to the text.

Asperal 09:22, 8 November 2007 (UTC)

Invitation to Participate in a Survey

dear Wikipedia Administrator ,

thank you for your kind attention to this message.

My name is Zhan Li and I am a PhD student at the University of Southern California's Annenberg School for Communication. ( You can view my bio (scroll down) for verification here: http://annenberg.usc.edu/Faculty/Doctoral/1.aspx )

I am asking approx. 200 randomly selected Wikipedia administrators if they would like to participate in a brief (it might take you about 10 minutes) online survey about their use of open content online encyclopedias. I am conducting this research for an introductory research methods class under Professor Peter Monge ( http://www-rcf.usc.edu/~monge/ ).

I hope that, if possible, you will participate in this survey. Please note that you must be 18 years older or over to participate.

Here is the link for the online survey, which begins with information pages detailing survey conditions and participant rights as well as my contact details for any questions:

http://www.surveymonkey.com/s.aspx?sm=a73oeHUjW9QKvYB7fmIb0A_3d_3d

The survey will close at Pacific Standard Time 12:15 AM on Wednesday 14th November. If you have any problems accessing this link, please let me know.

I appreciate your consideration of this request.

Thank you very much Zhan Li ( email: zhanli at usc dot edu ) Zhanliusc 07:55, 8 November 2007 (UTC)

Fsswsb question

In regard to User talk:ArglebargleIV#Fsswsb, I think I'm confused here. I don't quite understand what I did to make things more difficult for you. I'd like to know so I don't do it again -- believe me, I certainly don't want to make life difficult for any administrator, y'all have enough on your plate as it is. Thank you. -- ArglebargleIV 14:56, 8 November 2007 (UTC)

• Ah, thanks for the explanation. I get it now, and you're absolutely right -- I think that he should have been blocked for that, and I should have got somebody to do it rather than waffle around with another warning. I'll keep that in mind -- and thanks!! -- ArglebargleIV 18:38, 8 November 2007 (UTC)

Erdos Number debating getting out of hand, please help

Thanks for your comments at my talk page.

• First, yes, plainly anyone can comment at the deletion review page, I have myself. It's not plain that anyone can make endorse vs overturn "vote type comments". I take you to mean that techncally these are all just comments, there is no aqctual vote taken, and I am free to comment "overturn" even though I am not an admin.
• Regarding canvassing, Brownhairgirl has accused me of unethical canvassing at "ANI", see User_talk:PeterStJohn#ANI_re_your_canvassing. I have rebutted at the link she gave. I believe this is a deliberate ad hominem (and also, hypocritical) personal attack. I ask you please to read at least this one item. Brownhairedgirl has been eristic, faux-impersonal, hypocritical, and abusive for the entire debate regarding Erdos Numbers. I will gladly compile material to make a broad case, but there is no hope of objectivity unless we can address one clear, documented, falsifiable claim at a time. Since she has made a formal accusation against me this seems the necessary place to start, and I would very much appreciate admins looking at. Thanks for your consideration, Pete St.John 18:26, 8 November 2007 (UTC)

Pete, I have made a specific complaint about a specific and verifiable problem of canvassing. If you want to discuss it, the place to do so is at ANI, not by canvassing admins for support. --BrownHairedGirl (talk) • (contribs) 20:16, 8 November 2007 (UTC)

• Jitse, thanks for responding at my Talk page. Yes I made a mistake, and yes my temper is at risk, however, I did notify 3 of the 6 delete voters as soon as I notified the 11 keep voters, you can see the chronology in my contributions. One I skipped was an anonymous IP address and the other two were people that had been exceedingly active in the opposition, and who are active on that deletion review page, but who did not in fact post on this particular thread during that time frame. However, I believe that before posting the formal accusation at ANI, she should have checked the other delete-voters; I did in fact notify the majority of them, although my reasons for skipping 2 (discounting the anonymous IP) were not as well-founded as I mistakenly thought at the time. Pete St.John 20:32, 8 November 2007 (UTC)

Serious business disambiguation?

You've deleted Serious business several times. (This RFD log is typical.). I'm working on a replacement at User:Damian Yerrick/Serious Business, which I'd like you to look at before I take it to WP:DRV. --Damian Yerrick 18:53, 22 November 2007 (UTC)

Damian, thanks for letting me know. The article "serious business" used to redirect to "internet", which I (and many with me) thought was a joke not suitable for inclusion in an encyclopaedia. Your disambiguation page is very different. Thus, I don't think you need to go through Deletion Review. I don't know what Vary thinks, but as far as I'm concerned we just unprotect "serious business" so that you can put the disambiguation page there. -- Jitse Niesen (talk) 12:53, 23 November 2007 (UTC)

So then who unprotects and moves it? --Damian Yerrick (serious | business) 13:26, 23 November 2007 (UTC)

I'll do that but I first want to check with Vary. It's not good if administrators work against each other. -- Jitse Niesen (talk) 13:47, 23 November 2007 (UTC)

It's not a repost, so it clearly doesn't need to go to drv. I must have missed that he was planning on taking it there. -- Vary | Talk 13:54, 23 November 2007 (UTC)

Okay, all done. We might need to (semi)protect the disambiguation page in the future, but let's not worry about that now. -- Jitse Niesen (talk) 14:23, 23 November 2007 (UTC)

BCH

Hi, I am a bit of a novice in this, and I am not inclined to edit anything myself; but I would take issue with the entire paragraph on the "B-H" lemma in the BCH formula entry... A quick skimming of the references and the external links, e.g. the first one, suffices to argue that

--"BCH formula" is a clumsy misnomer. Historically, and manifestly in their original papers, Campbell and Poincare were the pioneers, Baker provided some minor intermediate results, and Haussdorff completed the theory group theoretically, as most recognize it today. Beyond the alphabetical convenience, "BCH" is really deprecated, and "CBH" may be preferrable, even while missing Poincare's name. "Formula" is also awkward, as, in general, no elegant closed formula is available: Dynkin's formula and the ones physicists prefer are implicit algorithms.

--"B-H Lemma" is flat misleading. The statement is, of course, a crucial lemma in deriving the CBH expansion; but only one of several, particularly well known decades before the CBH work. It is an elementary lemma in noncommutative combinatorics, provable in several ways recursively or as a solution to a linear operator ODE, as summarized in the references and the external links, and does Not require reality of lambda or hermiticity of A and B in any meaningful way. Somehow associating it with "quantum mechanics", which I have served for almost 40 years, is misleading and unfair to both combinatorics and quantum mechanics, at the same time! I would not plan to take action, but if somebody were, I'd recommend using consistent notation, X and Y, etc, instead of A and B, proper logic, and perhaps a terse indication that this Hadamard lemma is a preliminary result in the derivation of the CBH expansion.

Cuzkatzimhut (talk) 16:05, 26 November 2007 (UTC)

Hello. I'm sorry I didn't reply earlier to your message. I saw you did edit the article yourself, which is very good. I am not sure why you said that you don't want to edit yourself. If it is because you're new here, you really shouldn't worry. Everybody started as a novice. There even is an official rule here which says: Be Bold! I'm happy to help you, as are others. I'll definitely look over all edits you make to the article. My own knowledge about the BCH formula is unfortunately very limited, which is why I hope that you will continue edit the page.

Regarding the name, the rule is that we use the name which is used most often in the literature, even if that is somehow not a correct name. In the little experience that I have, "BCH formula" is used most often, but I'm happy to defer to your experience.

More consistent notation is of course a good thing. -- Jitse Niesen (talk) 21:14, 13 December 2007 (UTC)

Magnus series

Hello. Probably you could help clean up this mess. Michael Hardy (talk) 01:45, 6 December 2007 (UTC)

It's a bit short to call it a mess, but I guess I could write a nice article there. If only there were ten days in a week … But I'll put it on my to-do list. -- Jitse Niesen (talk) 21:18, 13 December 2007 (UTC)

Regarding computational formula for the variance

See my comment at the discussion page of the article in question in response to your question. Katzmik (talk) 13:17, 9 December 2007 (UTC)

Your note

Hi Jitse, people keep posting links to the article about the subject's supposed relationship with WP. It's self-referential, arguably quite insulting, and it's unlikely to be regarded as relevant to the article, which is anyway closed to editing. Therefore, there's no need to keep posting it on talk. Because it seemed gratuitous, I protected the page. SlimVirgin ^{(talk)(contribs)} 18:29, 17 December 2007 (UTC)

To third parties: The article in question is Carl Hewitt. JRSpriggs (talk) 02:50, 18 December 2007 (UTC)

Jitse's bot

Excuse me, but your bot seems to have slept through its normal editing period last night. Is it still working? Someguy1221 (talk) 23:40, 22 December 2007 (UTC)

On a side note, If/when it goes back up could you set the bot to change the "yesterdays' submissions" link at the top of the page to link to the previous day's archive? Someguy1221 (talk) 00:23, 23 December 2007 (UTC)

Thanks for your message. I'll have a look what's going on. -- Jitse Niesen (talk) 15:31, 23 December 2007 (UTC)

The bot is back up. Your second request (add a "yesterdays' submissions" link) is easy to do, but will take a couple of minutes. I'm afraid you'll have to wait a couple of weeks, when I'll have a decent Internet connection again. -- Jitse Niesen (talk) 16:27, 24 December 2007 (UTC)

Thank you very much. And...good luck with your interenet. Someguy1221 (talk) 19:35, 24 December 2007 (UTC)