wolfram-mathematica

问题 I am trying to use a list which is passed to a function in such a way that I can get the length of that list get the individual x and y values to manipulate The list I am trying to manipulate can be seen below: dataTan = Table[{x, Tan[x]}, {x, -1.5, 1.5, .75}]; this question is a sort of a follow-up to the question seen here. I eventually want to write my own function in mathematica that generates the Lagrange Interpolation polynomial for a given set of points {{x0, y0}, ... , {xn, yn}} I

问题 Considering the following example (from Sjoerd Solution on plotting a ConvexHull) Needs["ComputationalGeometry`"] pts = RandomReal[{0, 10}, {60, 2}]; dtpts=DelaunayTriangulation[pts] I would now like to plot the DelaunayTriangulation for a set of point but can`t figure out the Plot syntax using Graphics. Thoughts ? 回答1: Graphics[ GraphicsComplex[ pts, { Function[{startPt, finishPts},Line[{startPt, #}] & /@ finishPts] @@@ dtpts, Red, Point@Range[Length@pts] } ] ] And if you need real polygons:

问题 I am working on fairly large Mathematica projects and the problem arises that I have to intermittently check numerical results but want to easily revert to having all my constructs in analytical form. The code is fairly fluid I don't want to use scoping constructs everywhere as they add work overhead. Is there an easy way for identifying and clearing all assignments that are numerical? EDIT: I really do know that scoping is the way to do this correctly ;-). However, for my workflow I am

问题 Can a wireframe plot made with mathematica be turned into a transparent image and then exported to another site? The reason for this question is that I am trying to fit the wireframe to a structure. 回答1: The following code allows to export to GIF with transparent background (based on Mr.Wizard's code): g = Plot3D[{x^2 + y^2, -x^2 - y^2}, {x, -2, 2}, {y, -2, 2}, RegionFunction -> Function[{x, y, z}, x^2 + y^2 <= 4], BoxRatios -> Automatic, PlotStyle -> None, Axes -> None, Boxed -> False]

问题 For[n = 1, n < 6, n = n + 1, For[m = 1, m < 6, m = m + 1, abc = doc[[n]]; kk = doc[[m]]; v =vector[abc, kk]; vl = VectorLength[v]]] I want to store the data from each loop into an array or table form. How can I do that? 回答1: Try using a Table instead of two For loops. It returns a list of lists of the results (a matrix basically) Table[ abc = doc[[n]]; kk = doc[[m]]; v = vector[abc, kk]; vl = VectorLength[v], {n, 1, 5}, {m, 1, 5}] 回答2: It's not clear to me what data you want to save, but the

问题 Completing questions on how to plot a ConvexHull or a DelaunayTriangulation using Graphics in Mathematica, I would now like to plot the VoronoiDiagram within Graphics. Considering : Needs["ComputationalGeometry`"] pts = RandomReal[{0, 10}, {60, 2}]; vdpts=VoronoiDiagram[pts] 回答1: How about Needs["ComputationalGeometry`"] pts = RandomReal[{0, 10}, {10, 2}] DiagramPlot[pts] or am I missing your point? 来源： https://stackoverflow.com/questions/6477753/plot-voronoidiagram-using-graphics-in

问题 I have a very large table of data something like: lista = {{2,8},{3,4},{5,2}..} I would like to add x to every element so it would be lista ={{x,2,8},{x,3,4},{x,5,2}.....} This seems to me like it should be rather trivial but I have not been able to find a solution. I would appreciate any help. 回答1: This is very nearly a duplicate of Appending to the rows of a table and an exact duplicate of Prepend 0 to sublists on the dedicated site where your question should have been asked. Many more

问题 I wish to intercept assigning new values for the In variable. I have tried to do this by defining UpValues for In but it does not help in this case: Unprotect[In]; In /: Set[In[line_], expr_] /; ! TrueQ[$InsideSet] := Block[{$InsideSet = True}, Print[HoldForm@HoldForm[expr]; Set[In[line], expr]]] In /: SetDelayed[In[line_], expr_] /; ! TrueQ[$InsideSet] := Block[{$InsideSet = True}, Print[HoldForm@HoldForm[expr]; SetDelayed[In[line], expr]]] Is it possible to intercept it? P.S. This question

问题 I'm having problem with custom VertexRenderingFunction showing at different sizes for different graphs. An example is below, the default vertex rendering function has the desired behavior since vertices look the same in all graphs, any suggestion how to achieve that with custom vertices? (source: yaroslavvb.com) edges = Most[ ArrayRules[GraphData[{"Path", 5}, "AdjacencyMatrix"]]][[All, 1]]; doit[vrf_] := Print /@ Table[ GraphPlot[Rule @@@ edges[[k ;;]], VertexRenderingFunction -> vrf,

问题 This question is a continuation of a previous thread to compare two lists with the same length: Is there any efficient easy way to compare two lists with the same length with Mathematica? Given two lists A={a1,a2,a3,...an} and B={b1,b2,b3,...bn} , I would say A>=B if and only if all ai>=bi . Now we have k lists H={{a11,a12,a13,...a1n}, {a21,a22,a23,...a2n},...,{ak1,ak2,ak3,...akn}} , and want to find the maximum one if exist. Here's my code: Do[If[NonNegative[Min[H[[i]] - h]], h = H[[i]], ##