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Jul
13
comment How to construct a polyhedron from its vertex graph?
Slightly off-topic, but can you verify whether this sentence of the Wikipedia article is incorrect? "For a Tutte embedding, assigning attractive forces of equal magnitudes to all edges makes the forces cancel at all interior vertices..." But for the vertex to be the barycenter of its neighbours, the forces have to have magnitude proportional to the length of each edge instead.
Jul
12
comment Backsubstituting solution into FindRoot and Plot
Perhaps this should be a new question?
Jul
12
revised Backsubstituting solution into FindRoot and Plot
put the plots back
Jul
12
comment 3D Plot from 3 Polynomial Equations
You can do sol0 = Solve[f0[λ0, y0, y1, x, k] == 0, λ0] and sol0 = Solve[f0[λ0, y0, y1, x, k] == 0, λ0] to find the values of $λ_0$ and $λ_1$ that satisfy $f_0 = 0$ and $f_1 = 0$ respectively. Then substitute them into $f_2$ via sol2 = f2[λ0, λ1, x, k] /. sol0 /. sol1 // Flatten to get something that only depends on $x$, $k$, $y_0$, and $y_1$. However, there are apparently eight different solutions each to $f_0 = 0$ and $f_1 = 0$, so you'll end up with 64 possible values of $f_2$.
Jul
12
comment Why does FindFit seem to have trouble fitting exponential data?
Is the only difference between FindFit and NonlinearModelFit the fact that the latter provides more statistical information, or is there anything deeper than that?
Jul
12
comment Why does FindFit seem to have trouble fitting exponential data?
Try providing a reasonable initial guess: fit = FindFit[data, model, {{a, Last@Mean[data]}, {k, 1/First@Mean[data]}}, t]
Jul
12
comment Different colors when comparing Plot3D V9 and V10
Since this is the canonical solution, I'll delete my answer and leave this here: the previous default lighting settings.
Jul
12
comment Different colors when comparing Plot3D V9 and V10
Well, if you compare the first three images on the documentation page "Change the Lighting of Plots", which are supposed to look the same (and did in previous versions), it is clear that the default lighting has changed.
Jul
12
comment Different colors when comparing Plot3D V9 and V10
Ah! This is the better solution!
Jul
11
comment ParametricPlot - Problem with ColorFunction
I meant the tendency of some people to start accusing everyone who comments "Are you the downvoter?" "Are you the downvoter?". Often if someone reveals that they downvoted, the OP then goes and downvotes or leaves negative comments on their other unrelated posts. I'm not suggesting you would do that, I'm simply saying that one should not be expected to reveal one's votes, and asking whether one has downvoted should be considered an intrusive question.
Jul
11
comment ParametricPlot - Problem with ColorFunction
If you don't care then why call them a coward and ask for a reason?
Jul
11
comment ParametricPlot - Problem with ColorFunction
ColorFunction -> (ColorData["DarkRainbow"][Abs[2 #3 - 1]] &)
Jul
11
comment Neural Network and New Mathematica version
Summary of New Features in Mathematica 10, Ctrl+F "neural", no results. However, it does have a whole bunch of new machine learning functionality, so if you're not married to neural networks per se this might be useful.
Jul
11
revised Rough mesh lines in partially opaque 3D plots
edited title to remove ambiguity: is it the mesh lines or the plot that is partially opaque?
Jul
11
comment Rough mesh lines in partially opaque 3D plots
Works fine for me on Mathematica 9.0.1 on Mac. What's your version and platform?
Jul
10
comment Random numbers that sum up to specific value
+1: This is the approach endorsed by whuber and the statistics StackExchange. It also runs in only $O(n\log n)$ time.
Jul
10
comment Can mathematica rearrange an equation and solve/plot it?
You can also try ContourPlot3D[Sin[x + y + z] == x^2 y - z, {x, -5, 5}, {y, 0, 1}, {z, 0, 1}, ViewPoint -> {Infinity, 0, 0}, MeshFunctions -> {#1 &}, Mesh -> 20, ContourStyle -> None, Ticks -> {None, Automatic, Automatic}, AxesLabel -> {"", y, z}]
Jul
9
comment How can the opacity of a dense data set be automatically chosen?
That's pretty cool! I wonder what happens if you have two different datasets in the same plot -- are their point sizes adapted independently or are they the same? I can see arguments in favour of either.
Jul
9
comment Limits explanation in doc
Think of it as the direction you're going, not the direction you're coming from. (Although I do agree with you that it is a little inconsistent with the traditional mathematical notation. Perhaps they should have just used Above and Below for no chance of confusion.)
Jul
8
comment Implicitly differentiate an equation, then solve the resulting equation
Funny, this gives Indeterminate for f = x + y and 1 for f = x + y + z, both of which are incorrect.