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 Feb 6 comment MatrixForm in Mathematica MatrixForm acts as a "wrapper", which affects printing, but not evaluation. Further calculations can't be done with a matrix if you apply MatrixForm on it's definition. It is just a function to pretty print or visualize a matrix in Mathematica. Feb 5 comment Changing from Cartesian to polar coordinates in partial differential equation Here is the link @Kuba was referring to. Jan 31 comment How to find adjacent polygons of a specific polygon in a VoronoiMesh? @Odrisso I have added comments to the code for FindAdjPoly. Hope this helps you. About the visualization I am working on version 10.3.1 and I see no errors. The Table and Transpose is used to process the output polys so that HighlightMesh can make sense of it. Jan 29 comment Rewriting List of Matrix Equation in Terms of Individual Equations? In your case Thread[Equal[##]] & @@ Flatten /@ {M, A} Jan 25 comment Computing the logarithmic spectral norm rapidly How the limit is magically removed and a simplified formula takes the center-stage is out of scope of this answer. But it can be proven to be so using functional analysis apparatus on a Hilbert Space of operators. Here is the original paper by C. V. Pao. By now it is a standard result in the fields of dynamical systems and their stability. Jan 25 comment What would you ask Mathematica to do on a big system? Just feeling inquisitive. Will you mind posting a little snippet of the hardware spec from your OS. It must be a hell of a windows machine. Jan 19 comment GeoGraphics : path within a country The graph image was done with less mesh resolution (MaxCellMeasure -> .04) as it looks better and we can see the edges better. The GeoGraphics image is result of using MaxCellMeasure -> .004 which is probably a good setting for a fine mesh resolution. You are of course free to increase the resolution. Both the path will be same for a fixed MaxCellMeasure  setting. Jan 18 comment Adding a list up to a starting value FoldList[Plus, 5, {-0.1, -0.3, -0.1, 0.1, -0.1}] Dec 17 comment Find random $n$ combinations of values with a given sum Check arxiv.org/pdf/1507.00070.pdf algorithm 2 in page four. Don't know if it can be coded easily. Dec 16 comment How to replace a space by a comma Try this. expression = "{1 2 3 4 5 6 7 8}"; ToExpression@StringSplit[ StringReplace[expression, "{" | "}" -> ""]] Oct 11 comment Progress bar for FullSimplify Enjoyed reading it..+1 Sep 18 comment Nonlinear FEM Solver for Navier-Stokes equations in 2D Sorry I have no time to debug right now. You have to keep trying yourself at this time. Sep 18 comment Nonlinear FEM Solver for Navier-Stokes equations in 2D Please check the equation number {{1639}, {1671}, {1788}, {1827}} and you will see why FindRoot complains. Aug 20 comment Web Browsing Automation with Mathematica @ArnoudBuzing Are there any new functionalities added in the new version? Aug 4 comment Maximizing a 3-variable function You had a typo! Twice the constraint on x. By the way Maximize[{(a*x^2 + b*y^2), 0 <= x <= a, 0 <= y <= b, 1 < a, 1 < b}, {x, y}] prints $a^3+b^3$ and the other unbounded solutions too. Now for your original problem symbolic calculation becomes probably too involved to give closed form bounds in terms of {m,n,t}. Not sure if one can hack a solution in closed form here without any extra info on those constants. Aug 3 comment Maximizing a 3-variable function You have to provide some values for {m,n,t} or give some constraints. You can use Block to do that for example. Block[{m = 132, n = 10, t = 22}, NMaximize[{f[x, y, z], 0 <= x <= Min[t, z], 0 <= y <= m - z + x, 0 <= z <= n}, {x, y, z}]] gives me {5161., {x -> 10., y -> 61., z -> 10.}} if I use numerical version of Maximize. Jul 28 comment solving non-linear set of equations using NSolve in order to get all roots Here goes a numerical solution for you {phip -> -1.2873402582429818, t -> 414.62463948474345}. As far as I can see there is no real root for t<0. Also using Plot3D I doubt if there is any solution to {S1==0, S2==0} for t>0 and phip>1. Function is also unbounded in that region. Jul 24 comment Using Compiled Function in Implicit Region If you are unhappy with the warning message try this cf = Compile[{{x, _Real}, {y, _Real}, {z, _Real}}, -x y z]; TEST[x_?NumericQ, y_?NumericQ, z_?NumericQ] := cf[x, y, z]; RegionPlot3D[ ImplicitRegion[ TEST[x, y, z] > 0, {{x, -5, 5}, {y, -5, 5}, {z, -5, 5}}]] Jul 23 comment Solving an NODE in series You have two answers here as well as some informative comments. mathematica.stackexchange.com/questions/25363/… Jul 23 comment CompilationTarget to C takes long compilation time With Windows 8.1 and Visual Studio 2013 I am also getting 2 sec for f2. I guess its machine specific compiler issue.