Stephen Luttrell
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 Nov 15 comment Line Integral Difficulty You can evaluate this integral symbolically using Integrate[(x y)/(1 + x + 2 y) /. {x -> Cos[\[Theta]], y -> Sin[\[Theta]]}, {\[Theta], 0, \[Pi]/2}]. Nov 9 comment Creating rectangles from “ImageCorners” output boxes = image // Binarize // ColorNegate // ComponentMeasurements[#, "BoundingBox"][[All, 2]] & followed by Graphics[{FaceForm[], EdgeForm[Black], Rectangle @@@ boxes}] to verify the result. Oct 23 comment How to patch fingerprint ridges Do you have a greyscale image from which your binary image is derived? It would be better to use greyscale rather than binary as your starting point. Oct 22 comment Periodic boundary condition You can get Mathematica to solve this analytically by evaluating DSolve[{D[u[x, t], t] == D[u[x, t], x], u[x, 0] == Sin[\[Pi] Cos[x]]}, u, {x, t}], which gives {{u -> Function[{x, t}, Sin[\[Pi] Cos[t + x]]]}} in version 10.3. Oct 10 comment Image transformation to break up connected components Here's a solution: ImageCorrelate[image, GaussianMatrix[3]] // MaxDetect // ComponentMeasurements[#, "Centroid"][[All, 2]] & // VoronoiMesh // HighlightMesh[#, {Style[1, Red], Style[2, Opacity[0]]}] & // Show[image, #] &. The sequence of operations, reading left to right along the processing pipeline, is smooth to reduce noise, detect peaks, find centroids of peaks, convert to Voronoi mesh, highlight the mesh itself but make its cells invisible, overlay the mesh on the original image. Oct 7 comment Examples of using Mathematica to solve matrix equations symbolically NCAlgebra might be what you are looking for — see here . Oct 6 comment System cannot be solved with methods available It helps to start by visualising your function (difference between the left and right sides of your equation) by creating contour plots in the complex P plane, so you can see where the function's zeros are likely to be. For instance, you could start with ContourPlot[Abs[func[x + I y]], {x, 0, 10}, {y, -2, 2}] (Arg is done analogously). Oct 5 comment NSolve not working This works: NSolve[f1[x] == f2[x] && -3 < x < 3, x]. I arrived at this after I had a look at the plot Plot[{f1[x], f2[x]}, {x, -5, 5}]. Oct 3 answered HoldForm -> InputForm without processing the contents Oct 3 comment HoldForm -> InputForm without processing the contents The replacement HoldForm[x__] :> HoldForm[InputForm[x]] seems to do what you want. Sep 29 comment Why does this simple sum function fail to compile? The third argument of Compile might be what you need — e.g. Compile[{{x, _Real, 2}}, Sum[x[[i, k]]*x[[j, k]], {k, 5}, {i, 12}, {j, i + 1, 12}], {{i, _Integer}, {j, _Integer}, {k, _Integer}}]. Sep 22 comment Can I OCR Mathematica code on an image? You might be able to solve your problem by extending the method that I gave in my answer to Applying TextRecognize on alpha-numerical table. Sep 21 comment Challenge: deblurring images You can "improve" the blurred Lena image — call it lenablurred — with something as simple as Manipulate[Sharpen[lenablurred, r], {r, Range[1, 20], ControlType -> Slider}]. Sep 19 comment Approximate UnitStep for use in Enterprise CDF Yet again, I mistyped. fstr should be f. My apologies. Sep 19 comment Approximate UnitStep for use in Enterprise CDF To check string versus symbol input inside your Manipulate, evaluate this: Manipulate[Column[{Head[f], f, Plot[ToExpression[fstr][x], {x, -2 Pi, 2 Pi}]}], {f}]. In Mathematica, if I type Sin or "Sin" into the input field, followed by Return, then I get the expected sine wave plot in both cases, and some information about f. Now it's over to you to try this in an EnterpriseCDF. What happens? Sep 19 comment Approximate UnitStep for use in Enterprise CDF Of course, I meant to write InputField[Dynamic[x],String]. Sep 19 comment Approximate UnitStep for use in Enterprise CDF Is it not possible to use InputField[x,String], and then convert the string x to an expression using ToExpression[x]? I would be very disappointed indeed if at least the first step of this 2-step process doesn't work in an EnterpriseCDF, so I would like to hear whether InputField[x,String] works as expected in an EnterpriseCDF. Sep 9 comment Increasing the font size in the Vertexlabels of GraphPlot Insert EdgeForm[Black] at the start of the list of graphics commands. Sep 6 awarded Revival Aug 31 comment Avoiding misconversion of data with ToExpression function SemanticImportString might solve your parsing problem.