recently i started a mailing lists on Python and Java programing. I started it about a month ago, in which i give daily tips or commentary about them as i...
23
xah lee
p0lyglut
Feb 18, 2005 8:26 am
here's a problem that took me a while to find an answer. yesterday i've been updating the evolute page. ...
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Hop David
hollister_david
Feb 18, 2005 6:15 pm
... I want to learn some orbital mechanics and electrodynamics. So I'm interested in vector fields. Don't have a text handy but IIRC there are level surfaces;...
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xah lee
p0lyglut
Feb 20, 2005 1:46 am
hi Hop, you might find this wikipedia article useful: http://en.wikipedia.org/wiki/Vector_calculus Xah xah@... http://xahlee.org/PageTwo_dir/more.html ...
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xah lee
p0lyglut
Feb 20, 2005 1:47 am
ha ha, here's the answer: In[3]:= (1/f'[x])//InputForm Out[3]//InputForm= Derivative[1][f][x]^(-1) In[4]:= Format[f'[z],OutputForm] Out[4]= \!\(\* ...
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xah lee
p0lyglut
Feb 27, 2005 12:12 pm
here are 3 curves illustrating 3 cusps (at t=0) that has different curvatures. {t^2, t^3} {t^2, t^5} {t^2 + t^3, t^4} first case has curvature Infinity. Second...
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xah lee
p0lyglut
Feb 28, 2005 9:40 am
new page on cusps, with illustrations: http://xahlee.org/SpecialPlaneCurves_dir/Cusp_dir/cusp.html Xah xah@... http://xahlee.org/PageTwo_dir/more.html...
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xah lee
p0lyglut
Mar 2, 2005 10:16 am
Just created a page on curvature and tangent circle. See http://xahlee.org/SpecialPlaneCurves_dir/Curvature_dir/curvature.html the interesting idea is the...
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Xah Lee
p0lyglut
Mar 8, 2005 4:22 am
i just learned that the locus of cusps of parallel curves is the evolute of the given curve. this is interesting, because it is a alternative definition of ...
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Narasimham Gudipaty
glnarasimham
Mar 12, 2005 11:50 am
Yes,Xah, I also found it intriguing... the base circle is evolute of all parallel involutes, in perhaps the simplest 2D plane example. In fact,this is how...
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xah lee
p0lyglut
Mar 15, 2005 7:38 am
Some notes on “Scalar Field”, “Vector Field”, “Gradient”, “Divergent” A function that returns one real number is often called a Scalar Field. A...
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xah lee
p0lyglut
Mar 15, 2005 7:38 am
Nice connection of involute, evolute, and parallels. I've added some illustrations using sine curve as example. ...
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Xah Lee
p0lyglut
Mar 17, 2005 7:23 pm
I added a photo page on Curlicue. See http://xahlee.org/SpecialPlaneCurves_dir/Curlicue_dir/curlicue.html has anyone seen interesting examples? i know that...
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Xah Lee
p0lyglut
Mar 17, 2005 7:25 pm
recently i learned about: http://en.wikipedia.org/wiki/Ogee is there a geometric definition? Xah Lee...
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jpferrara06379
Mar 18, 2005 6:09 pm
This is just to describe the construct of the curve and then I want to ask what kind of curve is it, is it a parabola? Secondly how can I get into the math of...
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Narasimham Gudipaty
glnarasimham
Mar 20, 2005 4:25 pm
Let a ( = 10 ) be intercept on x- or y- axis . Any straight line is x / c + y / (a -c) = 1 is obtained by taking c as an arbitrary parameter. By C-...
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Joseph Ferrara
jpferrara06379
Mar 21, 2005 6:16 pm
Thanks for you kind reply. I will have to study this and perhaps I will have a further question. Joseph Ferrara ... ...
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xah lee
p0lyglut
Mar 29, 2005 8:21 am
added a folium of Descartes stamp! http://xahlee.org/SpecialPlaneCurves_dir/FoliumOfDescartes_dir/ foliumOfDescartes.html anyone know other stamps featuring...
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xah lee
p0lyglut
Mar 30, 2005 12:22 am
the one in mma version 2 is here: http://xahlee.org/SpecialPlaneCurves_dir/Seashell_dir/index.html formula is: x = 2*(1 - E^(u/(6*Pi)))*Cos[u]*Cos[v/2]^2, y =...
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garciacapitan
Apr 10, 2005 9:23 am
I am new in this group. I am a Spanish math teacher in a secondary school and I have a question about a curve. Let P mover on the ellipse x^2/a^2+y^2/b^2 = 1...
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mcyberliver
Apr 11, 2005 6:52 am
1) Is there a relationship between the focus of a parabola, its latus rectum, and its evolute? 2) The evolute of the spiral x= cost + tsint, y= sint - tsint...
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xah lee
p0lyglut
Apr 11, 2005 7:46 am
... by definition there is a relation between the focus and the latus rectum of a parabola. As to focus and its evolute, i suppose so, if not direct. ... the...
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Narasimham Gudipaty
glnarasimham
Apr 11, 2005 9:32 am
1) Is there a relationship between the focus of a parabola, its latus rectum, and its evolute? The 1.5 power curve has a cusp at focus. 2) The evolute of the...
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Narasimham Gudipaty
glnarasimham
Apr 12, 2005 5:58 am
An intersting 2D locus, however, I don't know its name. Perhaps the parameteric form is simpler. It is not difficult to derive a relation between th and an...
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xah lee
p0lyglut
Apr 14, 2005 8:47 am
interesting curve. i also find it interesting to know its application or how it came up. Xah xah@... ∑ http://xahlee.org/ On Apr 11, 2005, at 10:58...
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xah lee
p0lyglut
Apr 23, 2005 12:17 pm
just made an update to the breather surface, with graphing calc file & Mathematica file. http://www.xahlee.org/surface/breather_p/breather_p.html Xah ☄...
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Xah Lee
p0lyglut
Apr 23, 2005 5:03 pm
just created this page: http://xahlee.org/Whirlwheel_dir/reflecting_disks/reflecting_disks.html a photo gallery of reflecting disks. (radio dishes, solar...
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Hop David
hollister_david
Apr 23, 2005 8:31 pm
There was a toy that had a virtual pig floating in air. There was an actual pig at the base of the toy and his virtual image was at the focus of a parabolic...
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Narasimham Gudipaty
glnarasimham
Apr 24, 2005 12:55 pm
Breather breathtaking indeed !! Allow me acomment about related Three soliton surface with K= -1. One sees K > 0 areas in the peripheral regions of the...
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Narasimham Gudipaty
glnarasimham
Apr 24, 2005 2:50 pm
Better to say Reflector dishes instead of reflecting disks. The TV dish receiver is not necessarily parabolic, since the focus is below the center of the dish...
