Re: Sterographic plotting program
- To: mathgroup at smc.vnet.net
- Subject: [mg51250] Re: Sterographic plotting program
- From: mathma18 at hotmail.com (Narasimham G.L.)
- Date: Sun, 10 Oct 2004 01:57:24 -0400 (EDT)
- References: <cjtnf7$8gv$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Roger Mason <rmason at esd.mun.ca> wrote in message news:<cjtnf7$8gv$1 at smc.vnet.net>...
> Has anyone implemented a program to plot stereograms in Mathematica?
> Stereograms are used in crystallography to plot the positions of faces
> (and other planes) on crystals.[1]
In the following, Loxodromes making +/- 30 Degree to any meridian are
stereographically projected onto plane tangential to South Pole as
equi-angular/Logarithmic spirals. Please add 4 or 6 Loxos around polar
axis to get a full pattern. (Avoided it, as it may clutter up the
graphic). I remember a beautiful picturization similar to this in
'Mathographics' by Dixon Robert. A.,
New York, Dover, 1991.
Hope you get stereographic projections of icosa & dodecahedrons to
show, as precursors to crystallography..
Cheers,
Narasimham
a = 1; al = Pi/6; z = a*Tanh[Cot[al]*th]; r = a*Sech[Cot[al]*th];
x = r*Cos[th]; y = r*Sin[th];
loxo1 = ParametricPlot3D[{x, y,
z, {RGBColor[1, 0, 0], Thickness[.005]}}, {th, -Pi, Pi}];
loxo2 = ParametricPlot3D[{x, -y,
z, {RGBColor[0, 0, 1], Thickness[.005]}}, {th, -Pi, Pi}];
sphere = ParametricPlot3D[{a Cos[u] Cos[v], a Cos[u]Sin[v],
a Sin[u]}, {u, -1.5, 1.5}, {v, -Pi, Pi}, Shading -> False];
rst = 2 a r/(a - z); xst = rst*Cos[th]; yst = rst*Sin[th];
stereo1 =
ParametricPlot3D[{xst,
yst, -a, {RGBColor[1, 0, 0], Thickness[.006]}}, {th, -Pi,
Pi}];
stereo2 =
ParametricPlot3D[{xst, -yst, -a, {RGBColor[0, 0, 1],
Thickness[.005]}}, {th, -Pi, Pi}];
Show[{sphere, loxo1, loxo2, stereo1, stereo2}, ViewPoint -> {1.5, -1,
1},
Boxed -> False, PlotRange -> {{-3, 3}, {-3, 3}, {-1.01, 1}}];