User talk:RainerBlome

Welcome to my talk page!

Feel free to leave me a message, but be aware that it might be months until I notice it.

Original welcome message (left here because I like it, and for the links)
Hello and welcome to Wikipedia!

Here are some tips to help you get started:


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Pythgorean theorem & law of cosines
These are pretty firmly established math concepts for triangles, so the formula works. Yes, actually, really - as you have discovered: Merry Christmas! I see that you don't like having the Pythagorean theorem & Law of cosines mentioned in the article about spokes. Why do you consider your box (which I can't follow) to be better? Metarhyme 22:10, 25 December 2005 (UTC)

When I first found the formula on the web, I tried to understand why it should be correct. So I thought "How do I compute the length of a spoke?" and saw that a spoke is the diagonal of the described imaginary box. My explanation of the box is supposed to be understandable by everyone who knows basic trigonometry. Apparently it has to be improved. A picture would be nice here (fixed).

The Pythagorean theorem is implicitly used twice to compute the length of the boxes diagonal (d²=(a²+b²)+c²). This is true for all boxes, so I linked to rectangular box and saw no need to explicitly state that information on the spoke page. However, I just checked the box page and indeed, it does not show how to compute the length of the diagonal (fixed).

I do not see where the law of cosines should be applied here, can you explain? Which would be the sides of the triangle, where would the angle be? --RainerBlome 10:15, 3 January 2006 (UTC)


 * $$c^2 = a^2 + b^2 - 2ab \cos C . \;$$


 * looks like the law of cosines to me. The Pythagorean theorem is explicitly used once, in the first part of the spoke length calculation formula. The c in c² comes from the second part of the spoke length calculation formula - and that is the law of cosines, I would say. Do you agree?

Hm, "first part", "second part", what are you referring to? I do not understand your explanation. Anyway, I had a third look. Now I see how to apply the law of cosines to get the spoke length formula and added a corresponding paragraph to the article. Using the law of cosines yields (of course) the same result as doing $$(r_2 - r_1 \cos \alpha)^2 + (r_1 \sin \alpha)^2 = r_2^2 - 2 r_2 r_1 \cos \alpha + r_1^2 (\cos^2 \alpha + \sin^2 \alpha = 1).$$  You might say that this proves instead of uses the law of cosines. Going this way has the advantage (for me) that it's more elementary, no need to remember the law of cosines.


 * No original work is permitted in wikipedia, so if you figure something out, you need to find where someone else did it (citation) before placing it in article space.

The link to my source is there. The derivation section makes it easier to verify the formula.


 * You found the sides and angle with your look number three. A 3D diagram would be clearer. If I make one, I'll show it to you before I post it. I may add a technique to get accurate dimensions for cases where ERD and hub measurements don't exist or are suspect - akin to the calc walk through - and post it to Talk if I get around to it. Metarhyme 20:55, 3 January 2006 (UTC)

Hi there!
Seriously, I'm making this edit to say hello because this is the loneliest talk page for an active contributor I've ever seen. Keep up your good work. Keegan talk 05:27, 15 July 2007 (UTC)
 * Thanks. You too! --RainerBlome 11:40, 15 July 2007 (UTC)

Moore-Penrose pseudoinverse
Jmath666, Let's continue the discussion on the article's Talk page, where it is easier to associate and salvage discussion results to the article. --RainerBlome 09:03, 17 September 2007 (UTC)

Discussion at Talk:Elaine Herzberg
You are invited to join the discussion at Talk:Elaine Herzberg. —  IVORK  Discuss 00:27, 10 April 2018 (UTC)

Welcome to The Wikipedia Adventure!

 * Hi RainerBlome! We're so happy you wanted to play to learn, as a friendly and fun way to get into our community and mission.  I think these links might be helpful to you as you get started.
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-- 18:39, Saturday, December 14, 2019 (UTC)

Nomination of Proofs involving the Moore–Penrose inverse for deletion
A discussion is taking place as to whether the article Proofs involving the Moore–Penrose inverse is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or whether it should be deleted.

The article will be discussed at Articles for deletion/Proofs involving the Moore–Penrose inverse until a consensus is reached, and anyone, including you, is welcome to contribute to the discussion. The nomination will explain the policies and guidelines which are of concern. The discussion focuses on high-quality evidence and our policies and guidelines.

Users may edit the article during the discussion, including to improve the article to address concerns raised in the discussion. However, do not remove the article-for-deletion notice from the top of the article. Felix QW (talk) 14:59, 6 February 2022 (UTC)

Udwadia-Kalaba
Hi. I have enjoyed discussing with you the significance of Udwadia and Kalaba's formulation of constrained systems. Your response to me was good, but I would like more time to study your references to see if I now agree with you about its notability. This is in reference to our discussion at Talk:Udwadia-Kalaba formulation. As of now, when I study their paper, the result itself comes across as a relatively minor application of the M-P Pseudoinverse. In fact, the application of the pseudoinverse to project the dynamical equations to the tangent plane to the constraints is such a standard thing that no one I know (my included) has tried to write it up as a separate paper or call it a new formulation. Is there is a way for us to chat more to see if I can better convey my point of view to you, and also better understand why you think it is worthy of a page? Perhaps the talk page is the best way, but I think some of the issue is that we are not on the same page as to what constitutes a new formulation versus a widely used application of projection methods. --Madhu (talk) 01:50, 13 February 2022 (UTC)