User talk:Sam Derbyshire

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[edit] Swastika curve

Thank you for the image at Swastika curve, it is much improved (I had planned to replace it too). I have two suggestions. First, I wonder if you could make the text on the axes a bit bigger (the curve now looks great, but the text is still too small). Second, if you can, it would be great if you could provide the picture source code (at the image page), just in case it may need modification in the future (and that's a bit more in the free documentation spirit). Wonder what you think. You can reply here. Thanks. Oleg Alexandrov (talk) 04:41, 10 January 2008 (UTC)

There, I uploaded a better version. Feel free to tell me what you would like to see changed again (if anything). I hope that's all right. -- Xedi (talk) 08:39, 10 January 2008 (UTC)
Oh, by the way, what is the recommended font to use on mathematical images ? I remember seeing a manual of style for mathematical graphs but can't seem to find it anymore. If you see any images that need improvement (mine or not) I'll gladly try to help. Thanks. Xedi (talk) 10:33, 10 January 2008 (UTC)
Thanks. I'd argue that the font is still a bit blurry and may need enlargement, but that's up to you (here's the size I used at Bernoulli's inequality). I don't know about font type, see maybe WP:MSM, or Wikipedia:WikiProject Mathematics/Graphics, or ask at WT:WPM).
Also, since you make a lot of images, a long term idea would be to use SVG instead of PNG, as SVG is editable and I think works better for curves and other line art. But this is again a comment in the long term. Oleg Alexandrov (talk) 16:25, 10 January 2008 (UTC)
The idea was to have a higher resolution when clicking on the image, not a full resoluion image in the article. If you think it's preferable that the full size image is in the article, fine, but I thought it would be to small as there would be no higher resolution. About the font, I didn't find any information of those article. I think I remember someone recommending Computer Modern (the font used in LaTeX), but I don't think it goes too well (or maybe I haven't got a good version, I didn't really understand what I was supposed to download). As for the SVG, I don't really know how vectorising works - would I have to manually go over each line and draw it (like with the pen tool), or is the process somewhat automatized ? I don't think I have the time to manually convert those images to SVG. (Also, many of my images are actually animations, and for the moment browser support for animations is low, and I really don't see how I could convert my images to animated SVG in a reasonable amount of time). What do you think ? -- Xedi (talk) 18:09, 10 January 2008 (UTC)

My own philosophy is that it is good for an image to look good both in full resolution and in the thumbnail (as most people are looking only at the thumbnail in the article anyway). About SVG, from what I've seen MuPad exports natively to SVG (there's some command from that, or from the file menu). But again, the SVG remark was more about creating future images. I do agree that it is not worth it converting old images to SVG, and that animations can't be converted. Cheers, Oleg Alexandrov (talk) 20:10, 10 January 2008 (UTC)

Well the MuPAD SVG export feature doesn't really work well - often the font doesn't come out correctly, and some other bugs frequently occur. And, having had a look at the SVG that were created, they honestly aren't really editable nor convenient to work with. I do agree however that using SVG would be a good idea, just that I'm not a graphist and don't want to be approximating the curves by drawing splines in some vector image editing software. Sorry.
Sure, I understand. Thank you for the many very nice pictures you contributed. Oleg Alexandrov (talk) 04:19, 11 January 2008 (UTC)

[edit] Simplifying Complex Functions

I was wondering if MuPad had the ability to handle complex functions more intuitively. In particular, is there a way to set up a complex function and have MuPad extract the numerical values for the Real and Imaginary parts? With all of the tests that I've done I have ended up evaluating the real and imaginary parts and then plugging them into MuPad, which is quite complicated, especially when graphing the Absolute Value. Vjasper (talk) 06:57, 20 January 2008 (UTC)

In particular, how did you handle the Gamma function? I can't find anything that isolates the real and imaginary parts of the function. Vjasper (talk) 07:04, 20 January 2008 (UTC)
Well the Im, Re and abs (note the case) give the imaginary part, the real part and the absolute value, respectively. Does that answer your question ? -- Xedi (talk) 12:18, 20 January 2008 (UTC)
I understand what each of the graphs represent, I'm just curious what you actually plugged into MuPad in order to get them. That is to say, if you take the 3D example code, what actual function did you use for, say, the Real part of the Gamma Function? The reason I'm asking this is because, as far as I can tell, there isn't a good way to isolate the Real output of the Gamma function for complex input. In the case of things like, for instance, cos(z), you can expand it to cos(x + iy), then use the additive angle laws for Cosine in order to produce cos(z) = cos(x)*cosh(y) - i*sin(x)*sinh(y) (the hyperbolic functions coming, of course, from their relationship to the complex trigonometric functions). In this case you could easily use the left hand and right hand sides of the equation (those with and without an imaginary coefficient) to produce a graph of your Real and Imaginary parts, respectively.
My question is basically, how did you manage to do this with functions that do not have an explicit (or even implicit) formula with which you could substitute complex values in, and then try to solve and isolate the real and imaginary parts? With something like the Gamma function, there is no real way to express it (other than the integral, which isn't very helpful when dealing with complex functions), so how were you able to find some kind of function to give MuPad to graph? Vjasper (talk) 19:29, 20 January 2008 (UTC)
As I said, just use the Re, Im and abs. For example, for the gamma function, instead of the 8*sin(x-cos(y))+(x^2+x*y) I got at my example code, just plug in Re(gamma(x+I*y)) to get the real part, or Im(gamma(x+I*y)) for the imaginary part, or abs(gamma(x*I*y)) for the absolute value. Hope that helps. -- Xedi (talk) 21:56, 20 January 2008 (UTC)
Oh, wow. I didn't realize quite what you meant, but that's ridiculously simple. Thank you. Vjasper (talk) 04:24, 21 January 2008 (UTC)

[edit] Your rendering of LambertWAll.png is just indescribably beautiful

Your rendering of LambertWAll.png is just so beautiful. I don't know what else to say.

Does MuPAD select the hues for you? The color triad is exceedingly elegant.

-Aaron Hefel hefel.wordpress.com —Preceding unsigned comment added by 128.255.95.87 (talk) 17:18, 31 January 2008 (UTC)

No, I just chose the colors myself.
In MuPad, I chose : Red->CornflowerBlue for the real part, CadmiumYellow->SapGreen for imaginary part, and CadmiumYellow->Red for the absolute value. I just fiddled around with the colours until I obtained something nice.
Anyway, thanks. -- Xedi (talk) 17:26, 31 January 2008 (UTC)

[edit] The residues page graph

I'm just wondering how that function was evaluated, is it the real part or imaginary part? and what is does the hue display? Complex arguement perhaps? Just wondering =} 193.217.64.142 (talk) 22:58, 19 February 2008 (UTC)

You're right that I didn't say precisely so in the article, I corrected that. So the image is the absolute value of the function described in the text, and the hue just describes the height of the absolute value. There's absolutely no information in that plot about the imaginary part. Thanks for your interest and your correction. -- Xedi (talk) 23:10, 19 February 2008 (UTC)
Ok thank you, i was just wondering what the beautiful plot was. T.Stokke (talk) 14:55, 20 February 2008 (UTC)

[edit] Graph for counterexample

You seem to generate nice graphs! Can you please produce one for the counterexample? Schmock (talk) 20:14, 21 February 2008 (UTC)

Yes, sure, just added it to the article !
Be sure to ask if you have any other ideas for mathematical diagrams, I'm happy to help.
Thanks -- Xedi (talk) 04:02, 22 February 2008 (UTC)
Great, thank you! -- Schmock (talk) 10:24, 22 February 2008 (UTC)

[edit] Nice picture.

I like your pictures. They really help me understand my math books. --Sbluen (talk) 20:08, 1 March 2008 (UTC)

Thanks, it's nice to know that. Which ones in particular helped, and how ?
If you know of any topics for which it would help to have some more visualisation, I'd be happy to know. -- Xedi (talk) 20:18, 1 March 2008 (UTC)
Right now, I'm studying hyperbolic trigonometry, and your [[Image:HyperbolicAnimation.gif] helped me understand it. --Sbluen (talk) 20:44, 1 March 2008 (UTC)

[edit] My question on maths reference desk

You seem to be having trouble with all the questions (to whit 2, 4, 5 and 6) that involve the tap being on and the plug out at the same time. Under these circumstances, four gallons of water flow into the tank every minute and 6 gallons flow out. So what is the overall change in the amount of water every minute? Algebraist 13:08, 28 April 2008 (UTC)
  • If it is 2 gallons, is Q2. 10 minutes? Q4 6 minutes? Q5 14 gallons? And the last one 0 gallons? --217.171.129.79 (talk) 13:19, 28 April 2008 (UTC)
Yes, total flow = what flows in - what flows out, so here you get that the total flow is 4-6 = -2 gallons per minute (the minus sign shows that water is flowing out). So you got Q2 right.
For Q4, there are 20 gallons initially, and for the first four minutes, 2 gallons are flowing out per minute. After these first four minutes, how many gallons are left ? Then water flows out at 6 gallons per minute.
  • So four minutes of water flowing in fills it by 2 gallons, so there are 8 gallons in the tank. So the answer is 8 ÷ 6? So 1½? —Preceding unsigned comment added by 217.171.129.79 (talk) 13:39, 28 April 2008 (UTC)
For Q5, start at 20 gallons, it flows out at a rate of 6 gallons per minute for 2 minutes, then flows out at 2 gallons per minute for 3 minutes. Can you work out how much is left ?
  • 2 gallons?
For Q6, after 4 minutes there are 16 gallons as you said. After that, water is flowing out at a rate of 2 gallons per minute for six minutes. Can you see how many gallons will be left ?
  • 4 gallons?
Hope that helps -- Xedi (talk) 13:35, 28 April 2008 (UTC)

Did i get them right this time?

Answered on the Mathematics reference desk. -- Xedi (talk) 14:56, 28 April 2008 (UTC)

[edit] Wikimedia Commons

Thank you for uploading images/media to Wikipedia! There is, however, another Wikimedia Foundation project called Wikimedia Commons, a central media repository for all free media. In the future, please consider creating an account and uploading your media there instead. That way, all of the other language Wikipedias can use them too, as well as our many sister projects. This will also allow our visitors to search for, view and use our media in one central location. If you wish to move previous uploads to Commons, see Wikipedia:Moving images to the Commons (you may view images you have previously uploaded by going to your user contributions on the left and choosing the 'image' namespace from the drop down box). Please note that non-free content, such as images claimed as fair use, cannot be uploaded to the Wikimedia Commons. Help us spread the word about Commons by informing other users, and please continue uploading!

--OsamaK 06:59, 4 June 2008 (UTC)