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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.
Jan
3
comment Identify the independent variable in an expression
Yes, I would indeed. That doesn't mean that the other answers are bad, but if you strive for generality, then the goal has to be essentially emulating the behavior of Plot because you're doing an enhanced (and very nice) version of Plot. The question http://mathematica.stackexchange.com/q/8865/245 I referred to operates on much the same premise.
Jan
3
comment Identify the independent variable in an expression
@rogerl I guess it depends on the degree of water-proofing that's required in the problem at hand... but the reason I advocate closing this particular question as a duplicate is simply that it seems better to consolidate the fundamental ingredients under a single Q so as not to dilute the information.
Jan
2
comment Problem displaying “/” correctly in exported svg file of Plot in Mathematica 8
Indeed, there is a lack of padding in your first plot. But I think @Sascha has the right suggestion to fix that.
Jan
2
comment What is the function in Mathematica that can be used to find the derivative of a constant value function with respect to an arbitrary matrix?
Mathematica doesn't do symbolic derivatives with respect to matrices. The simplest way would be to define your matrices in component form and differentiate with respect to the components. It's not just a problem with differentiation - even the Dot product isn't defined when using just symbols that aren't explicitly matrices (or tensors).
Jan
2
comment Problem displaying “/” correctly in exported svg file of Plot in Mathematica 8
You could try my answer to How can I get Mathematica to include size information in exported SVG? because it fixes other problems, too. It might work for you because it also outlines all fonts (i.e., draws them as vector graphics). This can increase the file size but usually eliminates font problems entirely.
Dec
27
comment How do I keep Speak[] from spelling out words?
I think it will involve the same tricks as in http://mathematica.stackexchange.com/q/20513/245
Dec
27
comment Solve motion from Hamilton's equations
I've posted an answer based on a function that I wrote earlier. To get a more specific answer regarding your exact problem with differentiation, it would be necessary for you to post the actual Mathematica code you've tried.
Dec
16
comment Alter evaluation order when applying scalar multiplication to function
@Kuba OK, I've added an answer...
Nov
20
comment FDTD Electromagnetic Simulations with Mathematica
The question you're asking appears regularly in similar form, just with "electromagnetic" replaced by "some other field." The standard answer is that MMA is best for prototyping, not production code. It's great for combining (symbolic) analytical and numerical work.
Nov
20
comment FDTD Electromagnetic Simulations with Mathematica
Practically all the calculations in our paper "Surface plasmon polariton propagation around bends at a metal-dielectric interface" (link to ArXiV abstract) were done in Mathematica. But debugging can be hard in Mathematica too - and if you're not familiar with it, that can make it very difficult in practice.
Nov
20
comment FDTD Electromagnetic Simulations with Mathematica
You mention FEM in the question but FDTD in the title. The question is unclear to me. What exactly are you trying to do, what have you tried? Without a specific problem including code to get started, I doubt you can get a good answer. Of course Mathematica can solve time-dependent differential equations, but I can't think of anything beyond this trivial statement that would also fit into the format of a SE post.
Nov
20
comment Derivative of contour in ContourPlot
@AlexeyPopkov I think you're right. I haven't tried 10.3 - maybe that will fix it.
Nov
17
comment German Umlaut: how to forward through Run to the say command on OS X?
@Karsten7. I think it works fine, but my assumption is that the use of Run is important in this question for other reasons.