User talk:Geek3/Archives/2017

Share your experience and feedback as a Wikimedian in this global survey

Hello! The Wikimedia Foundation is asking for your feedback in a survey. We want to know how well we are supporting your work on and off wiki, and how we can change or improve things in the future. The opinions you share will directly affect the current and future work of the Wikimedia Foundation. You have been randomly selected to take this survey as we would like to hear from your Wikimedia community. To say thank you for your time, we are giving away 20 Wikimedia T-shirts to randomly selected people who take the survey. The survey is available in various languages and will take between 20 and 40 minutes.

Take the survey now!

You can find more information about this project. This survey is hosted by a third-party service and governed by this privacy statement. Please visit our frequently asked questions page to find more information about this survey. If you need additional help, or if you wish to opt-out of future communications about this survey, send an email to surveys@wikimedia.org.

Thank you! --EGalvez (WMF) (talk) 20:09, 13 January 2017 (UTC)

Your feedback matters: Final reminder to take the global Wikimedia survey

(Sorry to write in Engilsh)

Hello! This is a final reminder that the Wikimedia Foundation survey will close on 28 February, 2017 (23:59 UTC). The survey is available in various languages and will take between 20 and 40 minutes. Take the survey now.

If you already took the survey - thank you! We won't bother you again.

About this survey: You can find more information about this project here or you can read the frequently asked questions. This survey is hosted by a third-party service and governed by this privacy statement. If you need additional help, or if you wish to opt-out of future communications about this survey, send an email through EmailUser function to User:EGalvez (WMF) or surveys@wikimedia.org. About the Wikimedia Foundation: The Wikimedia Foundation supports you by working on the software and technology to keep the sites fast, secure, and accessible, as well as supports Wikimedia programs and initiatives to expand access and support free knowledge globally. Thank you! --EGalvez (WMF) (talk) 07:59, 24 February 2017 (UTC)

driven pendulum

Hello Geek, I saw your nice animation on https://de.wikipedia.org/wiki/Datei:Driven-pendulums-resonance-animation.gif and was wondering where did you find the idea! I hadn't seen it before in any book or textbook on physics and only recently found it described, back in 1813, by Thomas Young. (I'm currrently looking up some historical sources for the problem of forced oscillations.) I thought this nice way to demonstrate the forced oscillation must have been forgotten. Please let me an answer! --jbn (talk) 07:35, 20 March 2017 (UTC)

Bleckneuhaus, I had the idea on my own. it is straightforward from classical mechanics to illustrate a resonant pendulum like this. Usually, e.g. in physics textbooks, the amplitude is plotted against the relative frequency, because animations are harder to make and display, and plots are more accurate and quantitative. But this animation shows what is actually meant by a driven pendulum. If you are interested in similar illustrations, check out the source code, it also explains how the picture comes about. It should be mentioned, that driving a pendulum does not necessarily mean that the suspension moves, but it is one possibility. --Geek3 (talk) 14:32, 23 March 2017 (UTC)

Vectorfieldplot

Hi Geek3, I'm just a beginner in python and I'd like to plot field lines for three wires (equilateral triangle). What parameters do I have to change ??? At the moment I have field lines around only one wire and around the three... Thank you for your help, vector field plot is a great job !!! Best regards. J-M — Preceding unsigned comment was added by 81.66.186.177 (talk) 09:25, 27 March 2017 (UTC)

Just look at File:VFPt_hexapol_wires.svg for an example of six wires. Each wire is placed with one of the entries in the array called wires. Try

nw = 3; r = 1
wires = []
for i in range(nw):
    wires.append([r * cos(2*pi*i/float(nw)), r * sin(2*pi*i/float(nw)), 1])
field = Field({'wires':wires})

Then later on you also need to choose proper starting positions for the field lines in order to make their density proportional to the field strength. --Geek3 (talk) 18:59, 28 March 2017 (UTC)

Thanks...

Just wanted to thank you for the wonderful images of the electron orbitals. Exactly what I needed. I used them for my blog on physics - did credit you. https://readingfeynman.org It's really nice that - perhaps not consciously - you stuck so close to Feynman's treatment of the matter. It's amazing what your images did in terms of helping my understanding of what the wavefunction really is. Many thanks. Jean Louis — Preceding unsigned comment was added by 110.34.1.43 (talk) 04:44, 15 April 2017 (UTC)

Thank you Jean Louis, I'm really happy to hear that you find my work so useful! And by the way, you have an amazing blog, really impressive. I read it and I learned a lot. There is one especially interesting point you write about, namely the orbitals for m=-1,1 etc.. As you can see in my pictures, they are rings, where the sign determines if the complex phase increases clockwise or counter-clockwise. In some of the Wikipedia images these m-eigenvalues are falsely assigned to lobes in a certain direction e.g. x. But such orbitals are not eigenfunctions of one corresponding m-eigenvalue. Rather they are superpositions from two m-values of opposite sign, which makes the wavefunction real. --Geek3 (talk) 11:52, 16 April 2017 (UTC)

Marvellous works, Sir!

@Geek3:
Dear Sir,
Your images and animated gif files are marvellous works! More remarkable is your posting the source code as well. You are a good human being, and perhaps you don't know it, for your intent to disseminate knowledge among everyone, whether they are known to you or not. I admire your goodness, Sir!
Please refer to your created file File:Wave_opposite-group-phase-velocity.gif created by Mathematica.
Why did you use the equation: (5/8 - 3/8 * Cos[2 Pi (x - t)]) * Cos[2 Pi (10*x + 4*t)] ? What was the motivation for your using such equation, sir?
Please advise.
Regards,
Bkpsusmitaa (talk) 06:42, 25 April 2017 (UTC)

Thank you Bkpsusmitaa, I'm very pleased to hear that. The wave equation can be understood as follows: It is a product of a wave with an additional envelope. The wave Cos[2Pi(10*x+4*t)] has short wavelength (x/0.1) and moves left (+4t). The envelope has a constant offset (5/8) and a modulation (3/8Cos...). The modulation has a long wavelength (x/1) and moves right (-t). --Geek3 (talk) 21:27, 28 April 2017 (UTC)

Coulomb charges

Your plus-minus pair of Coulomb charges with electric-field lines is great, and I'd like to use it in a talk. Would that be OK, and, if so, how would you like me to credit you? — Preceding unsigned comment was added by 137.222.248.132 (talk) 08:22, 26 May 2017 (UTC)

Yes, the free license ensures that you are allowed to use my graphics. For the credit use a line like this: "© 2010 Geek3 / GNU-FDL, commons.wikimedia.org/wiki/File:VFPt_charges_plus_minus.svg" and adapt it to the specific image. --Geek3 (talk) 21:47, 26 May 2017 (UTC)

A barnstar for you!

Thank you Lucas, I feel very honored and happy that the effort I put in VectorFieldPlot was worth it. By the way, I also love your graphics!! Keep it up! --Geek3 (talk) 12:48, 5 June 2017 (UTC)

Coherent states

Hello, I would like to thank you for your beautiful animations about coherent states and squeezed states of the harmonic oscillator. They are really pretty and easy to understand. Moreover, I was looking for something similar about coherent states of the rigid rotator, but unfortunately on Wikipedia there's nothing about that. I am thinking about the idea of Porter (http://aapt.scitation.org/doi/10.1119/1.17340) to construct a state of the rigid rotator that has a probability distribution whose maximum value rotates around the fixed circle of the rotator at costant angular frequency. It should look like your animation of a gaussian distribution that oscillates between the harmonic oscillator turning points, but with a distribution that rotates on a circle over time. Are you able to do such an animation? Or can you give me an idea of how to change your code (the source code that you give on Coherent states Wikipedia webpage) in order to produce such an animation?

Thank you very much. Best wishes,

Andrea

Hi Andrea. Thanks for the idea, in fact one really just needs to change the formula of the wavefunction for that of the rigid rotator. One could plot it in a circle, but it's simplest to put the rotation angle on the x-axis. I give you an example: Quantum-rigid-rotator_1+2-animation-color.gif. Is this what you had in mind? --Geek3 (talk) 21:11, 13 July 2017 (UTC)

How to use... VectorFieldPlot?

Hey Geek3,

I am fascinated by you VectorFieldPlot script and would really like to use this in order to create magnetic field line visualizations. Unfortunately, I wasn't able to implement your script using MatLab or Mathematica. Is there any technical support or documentation about how to use the script in order to create magnetic field plots?

Thanks for your work and ideas, Daniel — Preceding unsigned comment was added by 128.176.12.170 (talk) 08:17, 12 July 2017 (UTC)

Hi Daniel. I'm happy you like the program. VectorFieldPlot is is not written in Matlab or Mathematica, and porting it would be quite some effort. You need to install python to execute it, which you can download for free. The project page User:Geek3/VectorFieldPlot has some documentation of the relevant commands. It's easiest to copy the code of an existing graphic and start playing with that. --Geek3 (talk) 21:18, 13 July 2017 (UTC)

Hey, Geek3, thanks again! Your help was quite successful since I was able to execute the code within python. It was no problem to start the basic source code but when I added an specific example, in my case your example "Cylindrical Magnet", I got many errors. Dou you have any idea how to fix this? Is it possible to contact you by mail in order to send you an example? Thanks, Daniel

Hi, send me an example to geek3@hulapla.de and also put the error messages that you got. Then I can probably fix it and send you a working example in return. --Geek3 (talk) 21:56, 14 July 2017 (UTC)

Hey, Geek3, thanks for your help. I send you an email! — Preceding unsigned comment was added by 128.176.12.148 (talk) 09:51, 19 July 2017 (UTC)

Hey Daniel, I received your email from two weeks ago and answered. But you sent me the same email again on 26.. Is it possible that my answer went in your spam folder? Basically from your error messages it becomes clear that the problem is you're missing the lxml library (http://lxml.de/). Additionally I recommend you to put the whole script in one file and execute it with python rather than pasting all the lines into a console. That way you can see easier where the first error occurs. --Geek3 (talk) 19:22, 30 July 2017 (UTC)

Spheroids

Hi, I appreciate your images of spheres (e.g. File:Sphere wireframe 10deg 6r.svg). I was considering adjusting these to create images of oblate and prolate spheroids, since I don't see any high quality SVG versions in Category:Oblate spheroids or Category:Prolate spheroids. However, my adjustments to an original SVG would just be a matter of stretching a dimension. Perhaps you may want to modify your fancy python code to generate these spheroids? Cheers, +mt 01:23, 1 September 2017 (UTC)

Hi Mwtoews, thanks for asking. It's clearly better to create some spheroids by modifiying the code instead of stretching the 2D-projections. The latter ones would clearly exhibit some errors such as sheared lines and being stretched along another axis than the intended axis of symmetry. I will post a couple of spheroids soon together with the generating code that can be modified for similar purposes. --Geek3 (talk) 21:53, 2 September 2017 (UTC)

Yup, stretching a sphere into a spheroid would certainly shear and distort the representations of lines. Thanks for taking a look! +mt 03:11, 4 September 2017 (UTC)

VectorFieldPlot - fieldline calculation for coil

Hi, first of all - great work for all your contribution to wikipedia! I like the most the VectorFieldPlot script. I am trying to understand the code (mostly the math/physics part of it). Can you please explain how functions fa() and fb() for coil were derived (starting on line 1350)? Thanks a lot! — Preceding unsigned comment was added by 95.105.148.39 (talk) 21:48, 10 September 2017 (UTC)

Hi, thanks for your appreciation. Looking at the code today, I see that the mathematical functions could have been explained better... Nevertheless I hope I can make it understandable to you: The field of a coil can for instance (as done here) be computed as the sum of fields of all currents on the coil surface. Every infinitesimal current creates a field according to the en:Biot–Savart law and the sum can be obtained via integration. Unfortunately the 2D integral cannot be fully resolved, that's why we integrate numerically over one coordinate, namely the angle around the axis of symmetry (ig.quad in line 1362). In order to avoid the very slow 2D integration, the integration along the axis of symmetry is resolved analytically and that result is fa and fb. B is a vector field with two nonzero components. Both have to be computed. Instead of global coordinates x and y we use rotated and normalized coordinates a and b, because then the formula can be expressed in simpler terms. a is along the axis of symmetry and b along the radius. fa and fb are the respective components of the resulting field. I cannot explain the entire formula in line 1353 but it's the result of integrating the axial B-field component from the Biot–Savart law.--Geek3 (talk) 22:08, 10 September 2017 (UTC)

Oh, and in case it helps you: An alternative and possibly simpler way to compute the exact identical field outside of a coil, is to place two homogeneously charged round disks at both ends of the bar magnet and compute their electric field. This only requires Coulomb's law instead of Biot-Savart. An example is demonstrated in the code of File:VFPt_magnet_H.svg. However you will still have to solve an integral over the disk areas. --Geek3 (talk) 22:41, 10 September 2017 (UTC)

Thanks for reply. I am studying the Biot-Savart law. Actually in most of the materials from universities is the "classic example" where the point is in the axis of rotation. Once you step out of the axis, the formulas are getting pretty complicated. When it comes to coil vs. charge disk - those 2 methods produce the same field outside the coil, but different inside. Which one of them is the right one for cylindrical bar magnet with homogeneous magnetization? In the calculation - can you use the magnetization property itself? — Preceding unsigned comment was added by 95.105.148.39 (talk) 12:20, 11 September 2017 (UTC)

Both fields, from the charged disks as well as from the surface currents are the right ones for the field inside of a cylindrical bar magnet with homogeneous magnetization. The surface currents give you the so-called B-field, whereas the charged disks give you the H-field (see VFPt magnets BHM symbols.svg). Both of them are good and useful and it really depends on the application which one you want. For instance if you cut long slits in axial directions inside the magnet, the field therein will be approximately the H-field, but if you cut a long slit in radial direction, the field therein is more close to the B-field.
Yes you can also use the magnetization property, i.e. adding or subtracting a constant field vector inside the volume to convert between the two fields. You could also integrate over infinitesimal dipoles in the magnetized volume. But then you even have a 3D integral and you have to integrate over a singularity for any point within the volume and depending on how you resolve it you will either get H or B. --Geek3 (talk) 14:27, 11 September 2017 (UTC)

File:SparkFun 6DoF-Breakout Magnetometer+Accelerometer LSM6DS3 13339-01.jpg

File:SparkFun 6DoF-Breakout Magnetometer+Accelerometer LSM6DS3 13339-01.jpg has been listed at Commons:Deletion requests so that the community can discuss whether it should be kept or not. We would appreciate it if you could go to voice your opinion about this at its entry. If you created this file, please note that the fact that it has been proposed for deletion does not necessarily mean that we do not value your kind contribution. It simply means that one person believes that there is some specific problem with it, such as a copyright issue. Please see Commons:But it's my own work! for a guide on how to address these issues. Please remember to respond to and – if appropriate – contradict the arguments supporting deletion. Arguments which focus on the nominator will not affect the result of the nomination. Thank you!

Hedwig in Washington ^(mail?) 05:33, 18 November 2017 (UTC)

Quality Image Promotion

Your image has been reviewed and promoted Congratulations! VFPt maxwell coil.svg, which was produced by you, was reviewed and has now been promoted to Quality Image status. If you would like to nominate another image, please do so at Quality images candidates. We also invite you to take part in the categorization of recently promoted quality images. Comments Maybe you could add the meaning of dots and crosses to the description. Good quality. --Basotxerri 18:20, 26 November 2017 (UTC)

Your image has been reviewed and promoted Congratulations! VFPt magnets BH.svg, which was produced by you, was reviewed and has now been promoted to Quality Image status. If you would like to nominate another image, please do so at Quality images candidates. We also invite you to take part in the categorization of recently promoted quality images. Comments Good quality. --Basotxerri 18:23, 26 November 2017 (UTC)

Your image has been reviewed and promoted Congratulations! VFPt metal ball grounded.svg, which was produced by you, was reviewed and has now been promoted to Quality Image status. If you would like to nominate another image, please do so at Quality images candidates. We also invite you to take part in the categorization of recently promoted quality images. Comments Good quality. --Basotxerri 18:23, 26 November 2017 (UTC)

Your image has been reviewed and promoted Congratulations! VFPt cylindrical coil real.svg, which was produced by you, was reviewed and has now been promoted to Quality Image status. If you would like to nominate another image, please do so at Quality images candidates. We also invite you to take part in the categorization of recently promoted quality images. Comments Maybe you could add the meaning of dots and crosses to the description. Good quality. --Basotxerri 18:23, 26 November 2017 (UTC)

--QICbot (talk) 05:20, 29 November 2017 (UTC)