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Apr
28
comment add a legend show the expression for each contour?
@qed Are you using Mathematica version 8? Then maybe you can use the solution to Creating legends for plots with multiple lines: Copy the first code block and then do this: autoLegend[cc,{Abs[x]^(1/2)+Abs[y]^(1/2)==1,Abs[x]+Abs[y]==1,Abs[x]^2+Abs[y]^2=‌​=1,Abs[x]^3+Abs[y]^3==1},Alignment->{.1,Center}] where cc is your ContourPlot.
Apr
28
comment Mesh and ParametricPlot
yes, that sounds like the best route. eschew Show... Gesundheit.
Apr
28
comment Mesh and ParametricPlot
So you are agreeing with what @cormullion essentially observed, too. The problem with changing the order of presentation in Show is that the purpose of setting Opacity in the first place was so that it can be placed on top of a Graphics that comes before the RegionPlot. So changing the order doesn't really seem to be a solution.
Apr
26
comment How can I completely remove the ListAnimate controls?
Closely related: Is it possible to insert an animated image into Mathematica notebook?
Apr
26
comment Graphing the sequence {$p_k$} = $\frac{c - a + dp_{k-1}}{b}$
@molekyla777 Of course, it alternates. I think I was simply seeing the absence of a two-term recursion, so I immediately ruled out a real smooth oscillation. But even a geometric sequence can alternate, giving a rather trivial form of oscillation.
Apr
25
comment Truncate High order terms
@DanielLichtblau Makes sense - sometimes people do get spoiled by the more idiomatic TraditionalForm and try to enter things in that more ambiguous way, too.
Apr
25
comment Truncate High order terms
@DanielLichtblau Yes - of course I already guessed that's why you wrote it that way (after posting the comment)...
Apr
25
comment Truncate High order terms
@DanielLichtblau Actually, since O[...] turns things into SeriesData anyway, you can even simply say Sin[1/f]+O[f,Infinity]^4.
Apr
25
comment Creating a Mathieu stability diagram
That's an excellent explanation. Separation in elliptic coordinates is already quite a bit trickier than polar coords...
Apr
25
comment Graphing the sequence {$p_k$} = $\frac{c - a + dp_{k-1}}{b}$
A simple closed solution shows that it won't oscillate: RSolve[p[n + 1] == c + d p[n], p[n], n].
Apr
24
comment Is there a better way to add elements to a Graphics expression repeatedly?
I wouldn't expect much improvement to be possible (while maintaining all points as graphics objects) since Dynamic does seem to go blindly through all display related elements that are wrapped by it. So I would use something like ListAnimate with prerendered graphics to achieve similar effects. But even then, rasterization is probably best.
Apr
24
comment Simple subtraction question
Maybe you could add: in this special case the same result can be achieved simply with a - 1.
Apr
23
comment Kronecker delta notation
You can enter the $\delta_{n,m}$ in a TraditionalForm equation cell, and then copy the equation into an input cell. That cell can then be evaluated if you allow Mathematica to interpret TraditionalForm input in the resulting dialog box. If you want more streamlined input, this is essentially the same as: Can I enter the traditional form for Binomial as input in an expression?
Apr
20
comment Manipulate for Electric Field
You definitely should write your code as a Module, making sure to end lines with ;. Once you've wrapped it inside a function with all variables localized, the displacement of the charge can be introduced as a function parameter.
Apr
20
comment Manipulate for Electric Field
The code you have is pretty slow, but fortunately the interactivity you are looking for is also very easily realizable by simply pre-rendering a Table of plots in which the charge location is varied step-wise. That list of images can then be quickly manipulated, most easily by using ListAnimate.
Apr
20
comment Little triangles appearing in a Mathematica region plot with “opacity” saved in a PDF file
If you don't want to convert to a rasterized format, then the solution to Avoiding grid lines inside filled area in RegionPlot exported as PDF appears to work fine here. That's why I would consider this a duplicate of the question linked here or in the above comment by @Steve D.
Apr
19
comment Why does Arrow not work well with Scaled coordinates in 3D?
@gpap That's a great example, very entertaining... somebody at Wolfram really should re-think the way arrows wok in 3D. This internal use of Scaled for the heads causes so much headache.
Apr
18
comment Why does Arrow not work well with Scaled coordinates in 3D?
@gpap I just added an answer - my own approach was simply to avoid scaled coordinates as much as possible...
Apr
18
comment Why does Arrow not work well with Scaled coordinates in 3D?
I think this is closely related to an issue I addressed on my web page some time ago. I agree with @Kuba that it's not expected behavior. If you want, I could post the arrow function from my web site as an answer...
Apr
18
comment A Box for the integral or partial derivative d
One problem with these constructs is that they contain merely formatting and cannot be re-used as input if you copy them from the output cell. I thought you may be looking more for something along the lines of this, where I made sure the interpretation of the formatted output is preserved. But I guess you're happy with the solution you found... there isn't anything really simpler I can think of.