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Sep
23
comment Combining many plots with Show produces wrong x-axis position and wrong filling
The problem is that the filling is generated to fit within each individual plot range. So just set the PlotRange in each of the plots individually, rather than just in the Show command. That way, the filling will fill the whole common plot range.
Sep
19
comment Understanding differences between Maple and Mathematica in examples picked by Maplesoft
@DanielLichtblau Oops - better?
Sep
18
comment Short form of Graphics
Sorry, I posted a comment since I looked at your post quite quickly. Does Plot[x, {x, 0, 1}] // Options help?
Sep
18
comment Short form of Graphics
How about Plot[x, {x, 0, 1}] // InputForm // Short? Or, if you need more control, Short[InputForm[Plot[x, {x, 0, 1}]], 10].
Sep
17
comment Kernel crashes when plotting $z=\sqrt{(x^2 + y^2)}^0$
@Mr.Wizard Yeah, I'm fine with that.
Sep
17
comment Kernel crashes when plotting $z=\sqrt{(x^2 + y^2)}^0$
@Mr.Wizard I flagged it as such but did not downvote. Both "answers" seem to be simple comments to me but I can't say that I feel strongly enough to make a meta post.
Sep
15
comment How to manipulate a circle in GeoGebra style?
Personally, I preferred the original circle based version - which garnered my upvote. While it didn't replicate the GeoGebra behavior exactly, it certainly got the same idea across and with much simpler code. Furthermore, it's not clear from the question that an exact replication was necessary - at least not to me.
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
@belisarius Your question seems to be exactly opposite of the one here - namely, Plot[Derivative[f]...] uses a finite difference scheme on discrete functions, such as IntegerPart, Round and several others.
Sep
12
comment Speed of ConvexHullMesh
So, should the question be closed?
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
Incidentally, Derivative is not protected, so you can easily define your own DownValues: Thus, Abs'[x_] := Sign[x]; Abs'[0.5] produces 1.
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
Well, I guess it's not just D but the general fact that symbolic computation assumes symbols are complex. Many computations performed by Mathematica must be fully understood in this context - from Simplify[Abs[x^2]] to the apparent missing branch of the cube root in Plot[x^(1/3), {x,-1,1}]. There are exceptions, particularly the CubeRoot and Surd functions introduced in V9 but, generally, computations are done in the complex numbers and I assure you that this is the context in which you need to explore your question.
Sep
12
comment Solve Laplace equation using NDSolve
@SantiCarmesí The gradient field issue is discussed in great detail here.
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
A similar thing happens with Re and Im. While those functions are obviously meant to work in the complex realm, I think an understanding of what is going on there is relevant. This discussion might help in that regard.
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
It really doesn't matter if you agree or not - the basic fact is that D works in the complex domain and these functions are not differentiable in that context. That, quite simply, is the explanation of the behavior you see. Now, whether you would prefer different behavior and how you might implement it is a different question.
Sep
12
comment Strange behaviour of MMA in derivatives of some standard functions
The functions you explore are all non-analytic as complex functions, thus the derivative is undefined. You might explore the numerical derivative ND as defined the NumericalCalculus package.
Sep
11
comment Homotopy Visualization
I did something like here to illustrate graph isomorphism. That's much simpler, though, really. Shouldn't be to hard to grab a set of points describing the boundaries of the objects but it might be tricky to maintain the topological integrity throughout the animation.
Sep
11
comment Homotopy Visualization
I guess you mean a homotopy, actually.
Sep
10
comment How do I plot the images of oriented curves under complex transformation?
How about Show[r1, r1 /. Line[pts_] :> Arrow[pts, 2]]?
Sep
9
comment Calculating a potential function using the finite element method
@Hugh There certainly are other ways to make a mesh. In this answer I show how to interface with a free, third party program called triangle that might do what you want. However, I'd think that converting them to the ElementMesh format that you want would be rather involved. Also, V10.0.1 is due out any day and I'm quite certain that bugs in mesh generation have been addressed, though I'm not certain if this specific issue is improved or not. Will definitely be worth checking out, though.
Sep
9
comment Möbius transformations revealed
@YvesKlett Seems like a reasonable expectation. :) I do have an implementation based on simple graphics primitives that I'll post soon.