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  • Founded: Dec 12, 2000
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#1656 From: "gjmcclure" <greg_mcclure@...>
Date: Mon Jan 18, 2010 4:21 pm
Subject: Graphs of electron orbitals...
gjmcclure
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Recently I found a site that contains the equations to create the graphs for the
electron orbitals (s, p, d, f...) but when I use Graphing Calculator to try to
recreate the orbital graphs shown, I don't get the same results.  The site is...

http://www.uky.edu/~holler/html/orbitals_2.html

The graphs are shown by chosing the orbital in question from the left column,
the equations are shown by clicking on the equations reference on top.

I am making an assumption, which may be the problem... the graph would be of the
form r = f(theta, phi), so I pick the phi from column 1, and theta from column
2.  If I only use column 1 (the phi column) then I get shapes that look like the
0 value orbital for each state (I take the absolute value to get the other half
for some of them).  But I can't get the theta sections to work, they give me
very wierd surfaces that don't look at all like an orbital.

Okay, what am I doing wrong here?

#1657 From: Craig David <craigda@...>
Date: Mon Jan 18, 2010 11:51 pm
Subject: Re: Graphs of electron orbitals...
dcraigx
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I'm going to take the easy way out here because I've got about 49 things that
need doing before classes begin.   Have a gander at the "Mathematical Physics"
section of

<http://web.lemoyne.edu/~craigda/Physics/Sims/Files/filelibrary.html>.

I've posted a gc file that plots spherical harmonics (which is what those images
of orbitals really are.)

For a REALLY cool application check out

<http://daugerresearch.com/orbitals/index.shtml>

David




On Jan 18, 2010, at 11:21 AM, gjmcclure wrote:

> Recently I found a site that contains the equations to create the graphs for
the electron orbitals (s, p, d, f...) but when I use Graphing Calculator to try
to recreate the orbital graphs shown, I don't get the same results. The site
is...
>
> http://www.uky.edu/~holler/html/orbitals_2.html
>
> The graphs are shown by chosing the orbital in question from the left column,
the equations are shown by clicking on the equations reference on top.
>
> I am making an assumption, which may be the problem... the graph would be of
the form r = f(theta, phi), so I pick the phi from column 1, and theta from
column 2. If I only use column 1 (the phi column) then I get shapes that look
like the 0 value orbital for each state (I take the absolute value to get the
other half for some of them). But I can't get the theta sections to work, they
give me very wierd surfaces that don't look at all like an orbital.
>
> Okay, what am I doing wrong here?
>
>

David Craig


<http://web.lemoyne.edu/~craigda/>

#1658 From: Christopher Young <cy56@...>
Date: Tue Jan 26, 2010 3:26 pm
Subject: New pages on ruled surfaces on website.
c56young
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A few more pages added to my GC website. Still entranced by the problem of ruled surfaces. Amazed that any frame that is strung with the same number of strings on each opposite side will always produce a doubly-ruled surface. Most of these files are GC4 files, and can't be run with GC 3.5. However, I hope that they'll at least get some interest going in how much can be done with GC4.

Clicking on most of the images of files will download a copy.

Chris Young












Christopher O. Young






#1659 From: Christopher Young <cy56@...>
Date: Sun Jan 31, 2010 3:20 pm
Subject: Quicktime movie on website of hyperbolas via "sweep lines"
c56young
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Still working out how to relate all these different approaches to conics.
Ultimately, will be in terms of projective geometry and Dandelin spheres, I
think. Probably no other clear way to unite them all.
Will have to shuffle things around a lot.

The good news is that small-size movies are working OK.

http://home.comcast.net/~cy56/ws1/Geometry/Analytic%20Geometry/Curves/index.html



2 of 2 Photo(s)


#1660 From: Christopher Young <cy56@...>
Date: Sun Jan 31, 2010 3:35 pm
Subject: Fixed error in formula for conics via focal parameter
c56young
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Had some non-matching subscripts for the focal parameters k relative to the eccentricities, so the major and minor axes of the ellipse and the hyperbola weren't coming out right.

Fixed below:


http://home.comcast.net/~cy56/ws1/Geometry/Analytic%20Geometry/Curves/index.html


item3



#1661 From: Christopher Young <cy56@...>
Date: Sun Jan 31, 2010 3:56 pm
Subject: Re: Projective geometry
c56young
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On Jan 31, 2010, at 10:40 AM, Steven Rubenstein wrote:

Chris,

Can you explain projective geometry to me in a nutshell?

Steve

Christopher O. Young
ChristopherYoung56@...

Everything that doesn't change when you project a figure, just as you'd project a slide on a screen.
Except that the projector can go both ways; a double cone.

Instead of angles and distances and so on staying the same, we have perspective properties such as the "cross-ratio" staying the same.

I've got a great diagram from Kleins "Elem. Math: Geometry" that I'm going to upload later. It relates the cross-ratio to the Inscribed Angle Theorem.

There are fewer invariants, but they're more fundamental. Most importantly, the exceptional cases due to points and lines at infinity are brought into the same category as the others.

At least, that's my best idea right now. Felix Klein is the one who gives me the most insights, but I've been rereading his books for years.




Projective geometry

From Wikipedia, the free encyclopedia

In mathematicsprojective geometry is the study of geometric properties which are invariant underprojective transformations. This means that, compared to elementary geometry, projective geometry has a different setting, projective space, and a selective set of basic geometric concepts. The basic intuitions are that projective space has more points than Euclidean space, in a given dimension, and that geometric transformations are permitted that move the extra points (called "points at infinity") to traditional points, and vice versa. The properties that matter in projective geometry are those that are respected by this new idea of transformation, which is more radical in its effects than can be expressed by a transformation matrix and translations; the first issue for geometers is what kind of geometric language would be adequate to the novel situation. It is not possible to talk about angles in projective geometry as it is in Euclidean geometry, because angle is an example of a concept not invariant under projective transformations, as is seen clearly in perspective drawing. One source for projective geometry was indeed the theory of perspective. Another difference from elementary geometry is the way in which parallel lines can be said to meet in a point at infinity, once the concept is translated into projective geometry's terms. Again this notion has an intuitive basic (railway tracks meeting at the horizon in a perspective drawing). See projective plane for the basics of projective geometry in two dimensions.
While the ideas were available earlier, projective geometry was mainly a development of the nineteenth century. A huge body of research made it the most representative field of geometry of that time. This was the theory of complex projective space, since the coordinates used (homogeneous coordinates) were complex numbers. Several major strands of more abstract mathematics (includinginvariant theory, the Italian school of algebraic geometry, and Felix Klein's Erlangen programmeleading to the study of the classical groups) built on projective geometry. It was also a subject with a large number of practitioners for its own sake, under the banner of synthetic geometry. Another field that emerged from axiomatic studies of projective geometry is finite geometry.
The field of projective geometry is itself now divided into many research subfields, two examples of which are projective algebraic geometry (the study of projective varieties) and projective differential geometry (the study of differential invariants of the projective transformations).








#1662 From: Steven Rubenstein <SJRubenstein@...>
Date: Sun Jan 31, 2010 3:40 pm
Subject: Re: Quicktime movie on website of hyperbolas via "sweep lines" [2 Attachments]
akaroy
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Chris,

Can you explain projective geometry to me in a nutshell?

Steve


Christopher Young wrote:
> Still working out how to relate all these different approaches to conics.
> Ultimately, will be in terms of projective geometry and Dandelin
> spheres, I think. Probably no other clear way to unite them all.
> Will have to shuffle things around a lot.
>
> The good news is that small-size movies are working OK.
>
>
http://home.comcast.net/~cy56/ws1/Geometry/Analytic%20Geometry/Curves/index.html
>
>

#1663 From: Christopher Young <cy56@...>
Date: Sun Jan 31, 2010 11:17 pm
Subject: Re: Applications of projective geometry
c56young
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On Jan 31, 2010, at 11:50 AM, Steven wrote:

What's the point?


On Jan 31, 2010, at 10:40 AM, Steven Rubenstein wrote:

> > Chris,
> >
> > Can you explain projective geometry to me in a nutshell?
> >
> > Steve

At this point, I can't give you a direct answer. But I think that's what physicists probably said about complex arithmetic and analysis, and now it's used throughout physics. You just mentioned that Sachs's theory was based on using quaternions.

Understanding the geometry of orbitals in a more unified way has got to be a help throughout physics.

Computer graphics would be much slower and more difficult without it.

Here's something I came across doing a Google search for "physical applications of projective geometry":




#1664 From: Christopher Young <cy56@...>
Date: Sun Jan 31, 2010 11:20 pm
Subject: Applications of projective geometry to relativity theory
c56young
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  1. [PDF] 

    Projective geometry and special relativity

    File Format: PDF/Adobe Acrobat - Quick View
    by D Delphenich - 2005 - Cited by 3 - Related articles
    [22] O. Conradt, The principle of duality in Clifford algebra and projective geometry, in. Clifford Algebras and their Applications in Mathematical Physics, ...
    arxiv.org/pdf/gr-qc/0512125


  2. Clifford algebra, geometric algebra, and applications

    Projective and conformal geometry. Various applications in physics (classical mechanics, electromagnetism, special relativity / Minkowski space, ...
    www.math.kth.se/~dogge/clifford/ - Cached - Similar
From the first paper:




#1665 From: Christopher Young <cy56@...>
Date: Mon Feb 8, 2010 2:03 pm
Subject: New web pages on implicit differentiation; one-sided surfaces
c56young
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#1666 From: Christopher Young <cy56@...>
Date: Mon Feb 8, 2010 3:22 pm
Subject: New web page on Möbius strip "space station"
c56young
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http://home.comcast.net/~cy56/ws1/Math/Topology/index.html

The idea is to make the concept of an intrinsic test of non-orientability clear
and vivid.
I'm a little worried about how I'm constructing the "space station", via
sweeping a fixed-size rectangular frame around.

It doesn't work too well when the surface self-intersects, since the walls of
the "space station" get pinched to zero width along certain lines. Back to the
drawing board as far as space station design goes. The big question is: Is it
possible to construct a self-intersecting one-sided "surface" with thickness?

These are files made with Graphing Calculator 4, still in development. However,
they're intended to show just how much GC4 is capable of, with minimal effort
compared to something like Mathematica when it comes to vivid, interactive
graphics with straightforward, mathematical specifications.

1 of 1 Photo(s)

#1667 From: Christopher Young <cy56@...>
Date: Mon Feb 8, 2010 3:35 pm
Subject: New web page on Möbius strip "space station", link corrected
c56young
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Sorry, that link is now:

http://home.comcast.net/~cy56/ws1/Math/Topology/mobiusSpaceStn.html

The idea is to make the concept of an intrinsic test of non-orientability clear
and vivid.
I'm a little worried about how I'm constructing the "space station", via
sweeping a fixed-size rectangular frame around.

It doesn't work too well when the surface self-intersects, since the walls of
the "space station" get pinched to zero width along certain lines. Back to the
drawing board as far as space station design goes. The big question is: Is it
possible to construct a self-intersecting one-sided "surface" with thickness?

These are files made with Graphing Calculator 4, still in development. However,
they're intended to show just how much GC4 is capable of, with minimal effort
compared to something like Mathematica when it comes to vivid, interactive
graphics with straightforward, mathematical specifications.

#1668 From: Christopher Young <cy56@...>
Date: Sun Mar 7, 2010 6:19 am
Subject: Quick ways to put grids on surfaces
c56young
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A quick easy way to get a grid is simply to select the "checkerboard" pattern:
You can increase the fineness of the grid via the resolution slider in the lower
left corner of the window:
If you want to get individual grid lines, you can just substitute in the "t"
parameter for one of the "u" or "v" parameters, and use a variable and a
parameter list for the other parameter. Below, I multiplied the ellipsoid
function by a number slightly greater than 1 to get the lines spaced out from
the ellipsoid so that they get graphed more neatly, although that's not strictly
necessary.



3 of 3 Photo(s)

#1669 From: Christopher Young <cy56@...>
Date: Wed Mar 10, 2010 6:43 am
Subject: Tips on drawing with the "t" parameter
c56young
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Here are some tips on how to use the "t" parameter to draw lines in 2D and 3D.

First, check out the Help section relating to Two-dimensional graphs:



Here's a file with the examples above plotted:



4 of 4 Photo(s)

#1670 From: Christopher Young <cy56@...>
Date: Sat Mar 20, 2010 3:31 am
Subject: xy grid superimposed on a surface
c56young
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What I want to be able to do is to see the x y grid superimposed onto the z axis,like the examples in the calculus textbook.

I think you must mean superimposed on the surface, right?

You can automatically put check marks which follow the xy grid just be selecting the checkered pattern:
One possible limitation of the pattern is that as the checks are made bigger (via the resolution slider), the surface becomes more jagged:


So, to overcome that, we can draw gridlines ourselves. In GC 3.5 we can use a parameter list
to graph each set of grid lines (parallel to the x axis and parallel to the y axis).

But, as I remember, for the latest Windows version we don't have parameter lists, so we have to plot each grid line separately:






5 of 5 Photo(s)

5 of 5 File(s)


#1671 From: Christopher Young <cy56@...>
Date: Sat Mar 20, 2010 3:44 am
Subject: Gridlines on surfaces, using defined function for the surface
c56young
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The whole process of putting gridlines on a surface becomes a lot simpler if we
put our surface into a function. Then we can define separate parameters using
"X" and "Y" with different subscripts. In every case, we're just plotting a
vector function of the form vector(x,y,z)=vector(X,Y,function(f,X,Y)). (You can
copy that last expression directly if the following graphic doesn't show up.)




#1672 From: Christopher Young <cy56@...>
Date: Sat Mar 20, 2010 3:57 am
Subject: Beware the grabby trigs!
c56young
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We have to watch out that GC doesn't grab expressions after the trig functions
and exponential function.
I personally would rather it wasn't quite so grabby. When typing a factor after
a trig function, be sure to enclose the trig function in parentheses so it
doesn't grab what follows as part of the argument. It's not enough just to type
an asterisk for multiplication (the way I wish GC behaved.)


#1673 From: Christopher Young <cy56@...>
Date: Sat Mar 20, 2010 4:07 am
Subject: Wireframe plots of surfaces
c56young
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If we use more closely-spaced values in our parameter lists, we can get really
nice wireframe plots. GC takes care of the shading of the lines very nicely.

In the windows version I don't think parameter lists are available. (Can
somebody using Windows let me know if you can open the file below?)
vector(x,y,z)=vector(T,k,function(f,T,k)),in(k,set(-2,-1.75,-1.5,-1.25,-1,-0.75,\
-0.5,-0.25,0,0.25,0.5,0.75,1,1.25,1.5,1.75,2))

#1674 From: "jls1934" <jls1934@...>
Date: Wed May 19, 2010 12:22 pm
Subject: accessing .gcf files from the web
jls1934
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Do any of you know if the following is possible, and if so how to do it?

I would like to embed links to .gcf files in a web site I am building. Users of
the web site can be assumed to have either GC or GCviewer on the machine they
are using to view the site. When I try to do this, clicking on the link to .gcf
file does not open the file but rather puts up a parameter list for the file the
user is trying to open.

Please help if you can.

#1675 From: Christopher Young <cy56@...>
Date: Fri May 21, 2010 3:00 am
Subject: Re: accessing .gcf files from the web
c56young
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On May 19, 2010, at 8:22 AM, jls1934 wrote:

Do any of you know if the following is possible, and if so how to do it? 

I would like to embed links to .gcf files in a web site I am building. Users of the web site can be assumed to have either GC or GCviewer on the machine they are using to view the site. When I try to do this, clicking on the link to .gcf file does not open the file but rather puts up a parameter list for the file the user is trying to open. 

Please help if you can.

The problem seems to be with the browsers, not with GC. In the Opera browser, you can specify that you want .gcf file to be automatically opened after downloading, by adding setting its MIME type to application/octet-stream, as described in the e-mail below.

On my website, I was able to get files downloaded, but in Safari they wouldn't open automatically after that. I had to use Opera (free) and add a special MIME type.

If you have any trouble, feel free to e-mail me again.




Chris Young

Begin forwarded message:

From: Walter Lee Davis <waltd@...>

Date: February 4, 2010 10:38:48 AM EST

To: freewaytalk@...

Subject: Re: [Express] Using Applescript to open a downloaded file?

Reply-To: freewaytalk@...


This is only working for you, on your particular copy of Opera -- just so you know. To make this universal, so others can have the same effect, you need to add that mime-type to the server.

Walter

On Feb 4, 2010, at 5:10 AM, Christopher Young wrote:


On Feb 3, 2010, at 5:03 PM, Christopher Young wrote:


Well, there doesn't seem to be an official mime-type for that, but you could use the catch-all application/octet-stream as the type, that just says "don't mess with me, I'm binary".

OK, I'll also try that.

With the Opera browser, I was able to add a new application, and set the mime type to "application/octet-stream". It seems to work; I can finally open files with one click!

Thanks again for the help.

Chris

_______________________________________________
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freewaytalk@...
Update your subscriptions at:
http://freewaytalk.net/person/options


#1676 From: Christopher Young <cy56@...>
Date: Thu Jun 24, 2010 8:03 am
Subject: Re: DROSTE EFFECT
c56young
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On Jun 19, 2010, at 7:44 AM, artplot101 wrote:

Hi Chris,

I have been trying to use this effect in GC. I read somewhere about it
and have been using a formula like:

z=z|z|^i2 to some effect. Maybe you've had more experience in this field? Or has it been addressed in GC before?


Art,

http://blog.wolfram.com/2009/04/24/droste-effect-with-mathematica/ has a nice implementation that can be applied to any photo, by the looks of it. If I have time, I'm going to see if I can get it to work with my copy of Mathematica, and then see if I can transfer any of that to GC. Great way to spice up the old family photos!

Chris


Two copies per spiral, resulting in octagonal forms

#1677 From: Christopher Young <cy56@...>
Date: Thu Jun 24, 2010 8:15 am
Subject: Re: DROSTE EFFECT
c56young
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On Jun 19, 2010, at 7:44 AM, artplot101 wrote:

> Hi Chris,
>
> I have been trying to use this effect in GC. I read somewhere about it
> and have been using a formula like:
>
> z=z|z|^i2 to some effect. Maybe you've had more experience in this field? Or
has it been addressed in GC before?

Art,

Your example produces some interesting curves! I'm still wondering exactly how
it works.
I guess any exponential spiral is going to have self-similar cells in an
exponential coordinate system.
The trick would be getting the images superimposed.

Chris


1 of 1 Photo(s)

#1678 From: Christopher Young <cy56@...>
Date: Thu Jun 24, 2010 8:39 am
Subject: More on Droste effect
c56young
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#1679 From: "artplot101" <arthur.lawrence@...>
Date: Fri Jun 25, 2010 3:38 am
Subject: Fractured Fractals
artplot101
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Complex operations in GC are amazing. You can abuse the examples and GC
keeps on ticking. In the Julia fractal, you also can change both g(z)
and f(z). See the file Spherical Fractal01.

Art

#1680 From: "artplot101" <arthur.lawrence@...>
Date: Sun Jun 27, 2010 12:19 am
Subject: COMPLEX NUMBER OERATIONS
artplot101
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Share your interest in the power of GC's complex number abilities.
Conformal Mapping and semi-Droste. Get the ho-hum outta your 2d graphics. See
the above subject in the FILES section. Thanks. Art

#1681 From: "jls1934" <jls1934@...>
Date: Sun Jun 27, 2010 3:04 pm
Subject: saving gcf files with text blocks
jls1934
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When I save a file in which I have added a text block, and then reopen the
file, the text block does not appear. What am I doing wrong?

#1682 From: "uwejagoda" <uwejagoda@...>
Date: Thu Aug 19, 2010 5:22 pm
Subject: Undefined in the domain shown
uwejagoda
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Hallo,
o.a. Subject wird angezeigt bei der grafischen Ausgabe von M = Wurzel aus
XX+YY+ZZ  .
Es handel sich hier um den Vektor einer Schwingung. Wenn ich einen Parameter
(Phase)
ändere, funkioniert es.

Wie sieht es mit einem upgrade aus  ( z.Z. GC 3.5)?


Uwe

#1683 From: "artplot101" <arthur.lawrence@...>
Date: Thu Sep 16, 2010 3:51 am
Subject: FORBIDDEN PLANET-THE END
artplot101
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I always wanted a remake of Forbidden Planet so I did the ending myself.
View Forbidden Planet in the files section. Artplot

#1684 From: Christopher Young <cy56@...>
Date: Sat Sep 18, 2010 4:11 am
Subject: Re: FORBIDDEN PLANET-THE END
c56young
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Very nice! Also a very educational example for complex functions.

On Sep 15, 2010, at 11:51 PM, artplot101 wrote:

 

I always wanted a remake of Forbidden Planet so I did the ending myself.
View Forbidden Planet in the files section. Artplot


Chris Young







2 of 2 Photo(s)

#1685 From: "Beth in MN" <beth.hentges@...>
Date: Sat Sep 18, 2010 6:21 am
Subject: loop animation?
bethhentges
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Is it possible to loop the animation?

In other words, I want the animation to run forward only and then to replay
automatically from the beginning without the slider moving backwards.

Thanks,
Beth

Messages 1656 - 1685 of 1978   Oldest  |  < Older  |  Newer >  |  Newest
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