amr

Dec
5
comment How does "curved space" explain gravitational attraction?
The best illustration I've seen of the equivalence principle and the basic curvature intuition of GR is in "The Mechanical Universe": youtu.be/w0SeFfV6J3k?t=13m
Oct
30
asked Prevent auto parentheses matching in Xcode
Sep
16
accepted List of all Visual Studio compiler errors and warnings, with their numbers
Sep
16
comment List of all Visual Studio compiler errors and warnings, with their numbers
Thank you. In keeping with my oath I actually did write a script and was almost done (just needed to fix some edge cases) but I lost it. Whoops.
Aug
30
comment Prove that G is a group
I find the reasoning is easier to follow if you draw out the table of a small group G (say 4 or 5 elements). For one, every element x must "shift" the elements differently, because otherwise you will have a row/column in G's operation table with a duplicate element, and that wouldn't be the table of a group.
Aug
30
comment IndexError: tuple index out of range ----- Python
I was getting this message because I was passing an array to a function that was expecting a variadic sequence of arguments (eg '{}{}'.format([1,2]) vs '{}{}'.format(*[1,2])
Aug
5
awarded Yearling
Jul
28
answered Type "myViewController" does not conform to protocol UIPIckerDataSource in Swift
Jul
20
comment Functions as objects
you might try replacing the output statements with Print[...]. i think the top-level behavior of newline-separated statements (as input into a notebook) is different when they're in a "formal" expression.
Jul
16
answered how to concatenate a list of a list of strings
Jul
15
comment How to create a thick spiral then extract the coordinates from the image?
Regarding the spacing/interval update in your question, it's not clear to me what the simplest approach to that is, and there's a couple mathematical issues (eg the spirals are close together at the center). Maybe figuring out how to make alternating black/white spirals that are exactly touching would be a good heuristic. The quickest way might actually be to ask on the Math.SE site.
Jul
15
comment How to create a thick spiral then extract the coordinates from the image?
@Solarmew See my edit for one solution to that.
Jul
15
revised How to create a thick spiral then extract the coordinates from the image?
added 1117 characters in body
Jul
14
comment How to create a thick spiral then extract the coordinates from the image?
I'm currently busy but I'll see if I can figure something out later today. In any case, feel free to re-accept to someone else's answer.
Jul
7
comment Image smoothing with own smoothing function
could you not use ImageFilter ? also ParallelTable would be a quick way to parallelize.
Jul
4
comment Matrix multiplication for higher dimensional matrices
to clarify here, MatrixForm is a display function. it's used to show your results as a matrix, but is not used during calculations. you don't need to tell Mathematica "hey this is a matrix" because any rectangular list of lists is as good a matrix as you need. for example Det[{{a, 1}, {Graphics[Disk[]], d}}] will give an answer. this is a deliberate design feature. in particular, it means that all the functions you use for dealing with lists (such as Reverse) can also be used directly on matrices... and vice versa.
Jul
3
comment Graphics3D artifact in Mathematica 10.1 64bit Home Edition - Windows 7?
could it be some kind of post-evaluation function that has attached itself to Graphics3D outputs that puts them in Pane? i don't remember what the commands are but the setting might be somewhere in AbsoluteOptions[EvaluationNotebook[]]. Actually, if this is the case it should be visible if you // FullForm the graphics3D output.
Jul
3
comment How to create a thick spiral then extract the coordinates from the image?
Just as an addendum, ImageCrop[image] is useful for cutting back exactly after over-padding (such as with PlotRangePadding in this case).
Jul
3
comment Graph, overlapping vertexlabels
This is probably the one failing of Mathematica's graphs presentation so far (poor handling of labels). Otherwise it's really pretty. Hopefully they improve labeling in the future. A couple things I would try here: Increasing/decreasing the ImageSize of the graph, as the labels don't scale in proportion to it. Removing the vertices altogether to get a cleaner graph, also fading down the edges a bit.
Jul
3
comment Using function to transform a list
Here is a version of the code to show a few different things/tricks: Fcoord[{n_, s_}] := Module[{x, y}, {y, x} = 100*If[Divisible[n, 30], QuotientRemainder[n, 30] + {1, 0}, {Quotient[n, 30], 30}]; s /. { "I" -> {x, y}, "II" -> {-x, y}, "III" -> {-x, -y}, "IV" -> {x, -y}}]; Fcoord /@ {{242, "I"}, {56, "IV"}} Note that Mathematica has functions for a bunch of stuff, even for things you would normally think are too specialized.
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