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Dec
22
comment polar form of generalized superellipse (not Gielis formula!)
Well, why don't you just fix $m=4$ in the Gielis formula to get the usual fourfold symmetry?
Dec
21
comment Creating curves that satisfy $f(x)\le g(x)\le h(x)$
"Exactly" like it? It sure looks to me like it was drawn by hand (in an illustration program).
Dec
20
comment How can I wrap text around a circle?
Unfortunately this answer is not on-topic for a Mathematica site. Otherwise we would have numerous answers on how to do this in Adobe Illustrator, in LaTeX, in PowerPoint, in SVG, and so on.
Dec
20
comment Randomly generate points on a van der Waals surface
For example, set s = DiscretizeRegion[ImplicitRegion[Min[EuclideanDistance[{x, y, z}, #] & /@ carbonXYZ] == rc + ra, {x, y, z}], {{-1, 28}, {-2, 23}, {-5, 5}}, MaxCellMeasure -> 0.1] and then RandomPoint[s] is extremely fast.
Dec
20
comment Randomly generate points on a van der Waals surface
Aren't you already aware of RandomPoint?
Dec
19
revised Convert large KML coordinate datasets to UTM
edited tags
Dec
19
comment Convert large KML coordinate datasets to UTM
I assume Keyhole Markup Language and Universal Transverse Mercator.
Dec
19
comment How to solve partial differential equation
There is no a or b in your code, so presumably you have some leftover variable definitions. Try clearing them.
Dec
18
comment How to find a starting value that is closer to the solution?
Wouldn't it be easier to (i) solve the first equation for $x$, (ii) solve the second equation for $y$, and then (iii) set $R = c/(y-x)$?
Dec
18
comment How to Plot StreamPlot of an ODE (particular case)
This is a limitation of Wolfram Alpha. Your code works fine in Mathematica: i.stack.imgur.com/U1tyM.png Questions about using Wolfram Alpha are not on-topic for this site: meta.mathematica.stackexchange.com/q/265/484
Dec
18
comment Plot region from given coordinates
Yes, that's fine, but why is that a problem? You say this approach "does not work", but the asker didn't ask for a convex figure.
Dec
18
comment Plot region from given coordinates
Why is it a problem if the FindShortestTour solution is not convex?
Dec
17
awarded  Revival
Dec
17
answered Limits explanation in doc
Dec
17
comment Plot region from given coordinates
See also How to ensure that Polygon[list] plots a simple polygon? and Rebuild a polygon so it doesn't self intersect
Dec
15
comment Interpreting the result of ContourPlot3D
Fundamentally this is because the ContourPlot* functions rely on the intermediate value theorem, which breaks down here because the function is not continuous.
Dec
14
comment Why doesn't Mathematica show up in OS X Spotlight?
I used to have the same problem. I deleted the Spotlight cache, which forced it to reindex the system, and that fixed it. You should try bill s's solution, which seems like a more non-violent way of doing the same thing.
Dec
14
comment How to Handle Infinity in calculations?
That sounds like a bad idea...
Dec
13
comment Plot a parametric function from $\mathbb{R}^2$ to $\mathbb{R}^2$
Can you post the function in Mathematica code? Look up Piecewise if needed.
Dec
13
comment Replacing Tan[x] with Sin[x]/Cos[x]
I don't know if this is what you're looking for, but (1 - Tan[x])/(Sin[x] - Cos[x]) // Simplify gives -Sec[x].