Reputation
Next tag badge:
1422/1000 score
185/200 answers
Badges
3 110 263
Newest
 Nice Answer
Impact
~968k people reached

Jan
19
comment Fitting a curve to an image object: not a superellipse, not an egg curve.. what else?
After using the method of @Dr.belisarius, the next step could be to use my answer here to find the center of mass and principal axes.
Jan
19
comment PlotLegend in Mathematica 8.0.4.0
BTW, autoLegend still works in Mathematica 10.3 as well. So if you use it, you also get cross-version compatibility!
Jan
19
comment PlotLegend in Mathematica 8.0.4.0
I would never use the PlotLegends package. That's why I wrote this answer here: Creating legends for plots with multiple lines. I still use that code myself in version 8, too. If this works for you, I would suggest making this a duplicate. The syntax would be simply this: autoLegend[Plot[{f[x],g[x]},{x,-4,4}],{"f(x)","g(x)"}] (after executing the code cell in the link).
Jan
18
comment Frame with round corners does not look the same in Working and Printout environments
I can confirm what @m_goldberg found on Mac. Just a guess: does it help if you set the ImageSize to a fixed value? Or perhaps try SetOptions[EvaluationNotebook[], WindowSize -> All] - these guesses are based on the hunch that the rounding radius (and/or thickness) is referenced to a different external length scale (outside the plot). In any case, it looks like a bug on Windows.
Jan
18
comment Animation, gif, ppt
Please let us know if the link given by @Kuba doesn't work for you. Otherwise, the question will be closed as a duplicate.
Jan
18
comment Using Solve to solve the equation $x^{1/3}=-1$
I agree with @MarkMcClure: the branch cut by default is along the negative real axis, and Solve looks for solutions among the complex numbers that form the image of $z^{1/3}$. The desired $-1$ is not in that set.
Jan
17
comment Forcing Mathematica to Output $1/\sqrt2$ as $\sqrt2/2$
There's a closely related question: Mathematica Sec and Csc. The title makes it seem not to be a duplicate, but the methods in two of the answers are applicable here.
Jan
16
comment FrameTicks not appearing with Export to .png file
In your example, you forgot to add Frame -> True so that the other options had no effect. A value for fontsize is also missing. But the main issue is valid: ticks aren't scaled properly. I was going to post a reply based on wrapping myPlot in Style[myPlot, Magnification -> 2]. This "sort of" works...
Jan
16
comment Simplification of rational function with Assume function
You have to put the Assuming at the beginning.
Jan
15
comment I need to multiply a series of matrices
Interesting observation about the limit of factors (+1). I didn't dare to try it for 10000 symbolic matrices, but I chose 100 to compare to my method. With that, I can still make my (non-parallel) method run about twice as fast as ParallelCombine by choosing UpTo[10] in Partition. The more matrices, the better ParallelCombine seems to get.
Jan
14
comment I need to multiply a series of matrices
@lucian You can use the new UpTo to fix that problem. I'll add something to my answer shortly.
Jan
14
comment I need to multiply a series of matrices
Maybe you can try to use Partition on your list, then ParallelEvaluate to use my answer on each sublist, then combine the results.
Jan
14
comment I need to multiply a series of matrices
I think that won't be an issue in typical applications. But I'm only guessing. Problems tend to appear only at very specific wavelengths but those isolated points could be dropped. That's just my blind guess, not knowing anything about your case.
Jan
14
comment I need to multiply a series of matrices
If your matrices are numerical, you could try to speed things up by using machine-precision arithmetic, e.g. by wrapping the list in N before doing the product. That would be much more of a gain than trying to parallelize the product.
Jan
12
comment How to make `D` apply chain rule on user-defined symbols as it does on `Dot` and `NonCommutativeMultiply`
But with Dt, you'd have to give up using Series - so I think it's of more limited usefulness. The good thing about Dt is that it allows you to identify what the differentiation variables is "after the fact," because there will always be Dt[_,y] terms that give it away. Then you can reverse the chain rule without affecting other prefactors.
Jan
12
comment Plot of 4-dimensional vector field
I'm afraid the question is too broad unless you give more concrete example. E.g., if there are conservation laws, they could help choose suitable variables for a lower-dimensional visualization. Or if only certain initial conditions matter, that could also play a role. I wouldn't know how to give a completely general answer.
Jan
11
comment How to make `D` apply chain rule on user-defined symbols as it does on `Dot` and `NonCommutativeMultiply`
Yes, that seems to work with Series, too. I guess Series doesn't do the same internal simplifications that happen when a higher-order D is encountered. By the way, I also had an idea based on using Dt instead of D... but I guessed you prefer sticking with D.
Jan
11
comment How to make `D` apply chain rule on user-defined symbols as it does on `Dot` and `NonCommutativeMultiply`
I'm assuming that the differentiation variables (y) is a scalar. Differentiation with respect to matrices or operators would require additional rules.
Jan
8
comment Labeling solutions of an Eigenvalue equation involving Bessel functions
@Aegon, I think I still have a factor wrong somewhere, so the bracketing still isn't quite right - will look at it some more... pretty sure it's fixable.
Jan
4
comment Join points or draw lines between them on a torus
I think this would best be added to the Q linked by @DavidG.Stork above.