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Dec
25
answered Prevent Plus from threading
Dec
25
comment Prevent Plus from threading
Thanks for all the answers, everyone! I guess I should have been more forthcoming about my ultimate goal, namely getting a correct PiecewiseExpand[f[t, 0, 2]] for my Koch snowflake parametrization, because I couldn't figure out make the answers here work for it. But seeing all the different approaches inspired a solution of my own that did work out (though still not as elegant as I would like).
Dec
24
asked Prevent Plus from threading
Dec
24
answered Revolution of Koch Snowflake
Dec
23
comment Eigenvectors choose intuitive ordering/sorting
But you said you want the eigenvectors of a diagonal matrix to form the identity matrix.
Dec
23
comment Eigenvectors choose intuitive ordering/sorting
In general what you are asking for is not possible. For example, the eigenvectors for $\begin{bmatrix}1&\epsilon\\\epsilon&1\end{bmatrix}$ are $(1,1)^T$ and $(1,-1)^T$ for any $\epsilon>0$, so there is no way for the eigenvector matrix to approach the identity as $\epsilon\to0$. You may have to write your own eigenvalue algorithm for your specific problem.
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 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 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.