Rahul Narain

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 1d comment Fourier Analysis: How to get rid of a discontinuity @Flymath: Ah, the problem is that one needs to "unwrap" the result of ArcTan before dividing by $\sigma\phi$. In this case it is apparently enough to just define g[σ_Real, ϕ_Real] = (If[# < 0, # + 2 π, #] &)@-ArcTan[Re[Ztri], Im[Ztri]]/(σ*ϕ). 2d comment Automatically lining up two images that have some common elements If this weren't a Mathematica-specific site I would suggest a simple manual technique using two minutes of Photoshop: i.stack.imgur.com/5Lm3z.jpg Jul29 comment Is it possible to plot a second-order curve by its non-canonical equation? Look up ContourPlot. Also, you need a space between x and y, otherwise it denotes a different variable named xy. Jul29 comment Express a complex function $f(z)$ as $u(x,y)+iv(x,y)$ Previously: Extract real part of a complex expression better than Re does, Does the Im function work with symbolic arguments?, How to simplify my expression to the style of “a+b*I”?. I probably should have searched for duplicates before posting my answer. Jul28 comment Is there a function for nearest power of 2 in Mathematica like nextpow2 in MATLAB? @Mr.Wizard Do you know if the v10 syntax is documented anywhere? Searching for @* in the documentation turns up nothing. Jul28 comment Piecewise Polynomial Interpolation Ah, right, one can't do the last example with Partition. In the original question the degree is constant, though, so Partition should be sufficient. +1 for the Piecewise and InterpolationOrder -> All. Jul28 comment Piecewise Polynomial Interpolation Instead of split can't you just do Partition[list, r+1, r]? Jul28 comment Zero-order interpolation not going fully around I think you ought to keep first-order interpolation and ask a question about how to get rid of the visual artifacts. Jul28 comment Undirected Network and its Monte Carlo Simulation "I want to connect the network like it originally was." If all you have are the coordinates of the points, how can anyone possibly know what the network originally was? Jul28 comment What is that Root[…] inside the answer represent? A polynomial of degree 5 has up to five roots. $k=1$ means take the first one. For example, Root[#^2 - 100 &, 1] is $-10$, and Root[#^2 - 100, 2] is $10$. Jul27 comment How Construct Clopen-Compact Bitopological Spaces? I don't think this is a question about the Wolfram Mathematica software... Jul24 comment How to generate nonperiodic tilings? Apparently the rt1s end up forming some of the dominoes and the rt2s end up forming the kites and the rest of the dominoes. Jul23 comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica? @blochwave, kale: I find that running Colorize on TotalVariationFilter@Sharpen@image works pretty well. Jul23 comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica? Half the reason I didn't post an answer was so that I wouldn't have to bother making the colours look good! So please, do direct any and all complaints towards @acl. Indeed, that blue is terrible, acl, what on earth were you thinking?! Jul23 comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica? @acl ColorFunction -> (Piecewise[{{Darker@Blue, # < 0.5}, {Red, # < 0.67}, {Darker@LightBlue, # < 0.75}, {LightYellow, True}}] &) Jul23 comment Using least independent rectangle area to separate every point I thought @Kuba had something like this in mind: nf = Nearest[Table[data[[i]] -> i, {i, Length@data}], DistanceFunction -> ChessboardDistance]; Colorize@Table[First@nf@{x, y}, {y, 0.03, -0.03, -0.0001}, {x, -0.05, 0.03, 0.0001}] but it doesn't work that well: i.stack.imgur.com/T22XL.png Jul21 comment An easier way to find the properties of an ellipse from its equation? I feel like the central question, "What is an intuitive way to find the major axis, minor axis, center, and rotation of an ellipse from its given quadratic equation?", is one better suited for the mathematics StackExchange. Once you have the mathematics, it should be short work to implement it in Mathematica. Jul21 comment Probable Bug in ConvexHullMesh I can reproduce this on OS X as well. Jul20 comment 2D Arrangment/Optimization Problem How about this: Fix $m=1$ and sort the entries of $A$. Jul20 comment Graphics3D flickers in Mathematica 10 and Linux "do others experience this?" I've been using Mathematica 10 on Fedora 20 (64-bit) with Gnome 3.10 and an nVidia GeForce GTX 480 with nVidia drivers and I have not seen this problem.