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location Munich, Germany
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I work at a small mechanical engineering company, where I develop software and image processing algorithms for camera-based inspection machines.


1d
comment Automatically lining up two images that have some common elements
@Mr.Wizard: ImageTransformation can wrap. If you have per-pixel offsets (as you would have with many optical flow or non-parametric registration algorithms), this question might be useful: mathematica.stackexchange.com/questions/31274/…
1d
comment how to calculate the coordinate of a point which depends on other points on a plane with specific distances
Have you tried something like FindMinimum[Total[(actualDist-targetDist)^2]], ...]?
Jul
25
comment Possible bug in Dynamic
@MichaelE2: You're right, this looks like a race condition: If I assign all Mathematica processes to a single CPU core, it doesn't crash anymore (or at least not that often). Maybe the WRI support people can't reproduce it because they have single core CPUs?
Jul
25
comment Possible bug in Dynamic
Yes, putting the ContourPlot inside Module[{x,y}, ... works, too. (I actually included that workaround in my WRI support ticket, but forgot it in the question here...)
Jul
23
comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica?
I don't think you should delete the question. There are no close votes, either. But most image processing questions at least contain some img = Import[url of a good source image] code snippet, so everyone can start playing around right away, and the resulting answers are comparable.
Jul
23
comment Plot a perfect looking circle using two functions, always look like an ellipse
@TimHUK: I think the idea is that the axes in Plot often show different quantities (e.g. meters versus seconds), where PlotRange->Automatic would make no sense, and often give extremely stretched results. So WRI chose a fixed ratio that's supposed to be pretty. (But that's really just guessing.)
Jul
15
comment Is it possible to calculate with declarations only?
Any program can be expressed as a Turing machine, without functions or variables, only states and a (potentially) infinite tape. I'm not sure if that's what you want, though.
Jul
13
comment Optimization Algorithm: ideas wanted
If you want to improve your question, show us a function that would "grade" different solutions, i.e. that would add up some distances, values, whatever, and the solution that gets the highest (or lowest) grade is the optimum.
Jul
13
comment Optimization Algorithm: ideas wanted
As it's stated, I think the optimal solution is to move the max in each row to the middle of the row. That way, no value is more than 2 rows away from the maximum.
Jul
13
comment Dynamic with RegionNearest keeps one CPU core at 100% - Is this a bug?
I reported this as a bug to WRI. I also found a reproducible way to crash the kernel using Dynamic, reported that too
Jul
12
comment Swap elements in list without copy
Did you try playing with the numbers? I find it hard to believe that Mathematica can copy a 8 GB list 100.000 times in less than 2 seconds. With a GHz CPU, it should take about a second (order of magnitude) to copy it once.
Jul
12
comment Swap elements in list without copy
But would it also copy the list if no other symbol referenced it? Otherwise, how do you explain @eldo's timing results?
Jul
12
comment Swap elements in list without copy
You could even get rid of the temp write: swap[list_, a_, b_] := {list[[a]], list[[b]]} = {list[[b]], list[[a]]}
Jul
12
comment How can I find out where a key binding is coming from?
@mfvonh: I just realized that my question was only half true: I did find another KeyEvent["9", in the same file, mapped to CreateInlineCell. I commented that out already - but it still seems to be active. Sadly, these EventTranslations seem to be completely undocumented.
Jul
12
comment Can you make the new “Choose color scheme” helper larger?
@Öskå: I thought questions regarding the current version don't get a version tag? That's how it was handled e.g. on this question: mathematica.stackexchange.com/q/15338/242 (version tag for version-9 was removed by rcollyer)
Jul
12
comment Can you make the new “Choose color scheme” helper larger?
Great! I can make the list longer by replacing ImageSize -> {Full, {200}} with ImageSize -> {Full, {600}} in 3 places (for gradient, indexed and physical). But I can't simply make it multi-column, because ListPicker doesn't support that.
Jul
12
comment Dynamic with RegionNearest keeps one CPU core at 100% - Is this a bug?
@Nasser: It crashed my kernel a few times, too. But every time I restarted the kernel and executed the same code, it worked. So I have no code to reproduce that problem.
Jul
12
comment Dynamic with RegionNearest keeps one CPU core at 100% - Is this a bug?
@Nasser: My original code had a LocatorPane to move pt around, containing a Graphics that showed a line from pt to the nearest point, and a RegionPlot of the intersection. I've simplified it to find the root problem, and only posted that. You can imagine a Locator moving pt around somewhere else in the notebook, but it doesn't really change anything.
Jul
11
comment Can StringTemplate be extended to offer printf-like formatting capabilities?
@m_goldberg: Maybe that sentence was a bit snarky ;-) Anyway, I can see the reasoning of offering no string template functionality, at least for a compiled language. (I'm not sure how you would write a large-scale application that can be localized to a dozen languages, but that's not the point here.) But MMA has string templates. It's just missing formatting options. As far as I can see, that doesn't make it safer, only harder to use.
Jul
7
comment Can I use symbolic tensors for simple linear algebra and calculus?
@Szabolcs: I've noticed that Dt[f.g, x] is f.Dt[g, x] + Dt[f, x].g: MMA seems to apply the product rule to Dot, so I'd say the 1 in 1 . x should be the Jacobian D[x,x], i.e. IdentityMatrix. (Did that make sense?). So I could probably safely replace Dot[x_,1] -> x. But I can't get the transpositions right, because D doesn't seem to work with Transpose, Transpose doesn't distribute over sums and so on.