https://community.wolfram.com RSS Feed for Wolfram Community showing questions tagged with Mathematica with no replies sorted by most viewed. https://community.wolfram.com/groups/-/m/t/516854 Hello, I am trying to use the HadoopLink package for the first time, and running into a few challenges. I am hoping someone out there is using this successfully, and might have some tips for a smooth installation in the current version of mathematica (10.2 at the time of writing this). I have downloaded the open-source project and I am following along with [HadoopLink installation instructions on GitHub][1]. I have unpacked the .zip and placed the HadoopLink folder (and only that folder, not the entire unpacked project) into my $User/Libarary/Mathematica/Applications folder, and loaded the package using: << HadoopLink` But when I proceed to the next step, and execute this code... link = OpenHadoopLink[ "fs.default.name" -> "hdfs://hadoopheadlx.wolfram.com:8020", "mapred.job.tracker" -> "hadoopheadlx.wolfram.com:8021"]; DFSFileNames[link] Mathematica output spews a bunch of Java exceptions (attached). Anybody have more detailed instructions on setting up HadoopLink? Maybe I should have put the entire project folder into the /Applications folder instead. I will try that now... [1]: https://github.com/shadanan/HadoopLink Caitlin Ramsey 2015-06-22T15:09:06Z https://community.wolfram.com/groups/-/m/t/435767 I have tried to find a solution to this problem in various places and thought I had it solved, but apparently not. When a Mathematica notebook is closed or Mathematica crashes, a lot of stuff is lost, even if a Save was just done. It’s not clear to me what kinds of things are lost but I believe it includes definitions. I have a large notebook for which some definitions are based on symbolic integrals that take a long time to compute, for example. I think that data can also be lost. Obviously I don’t want to re-evaluate the entire notebook every time I open it; in fact, I’m not even sure that would work due to the interactive nature of notebooks and the fact that typically one evaluates only part of a notebook and then another part. Here is what I have tried. I thought it was working in the past but it does not work now. There are two parts: one saves to a .mx file and one reads from the same .mx file. Note that my file path contains spaces. (* Save to .mx file. *) mxFileName = StringReplace[NotebookFileName[], ".nb" -> ".mx"]; DumpSave[mxFileName, Evaluate@Context[]]; and (* Retrieve from saved .mx file. *) mxFileName = StringReplace[NotebookFileName[], ".nb" -> ".mx"]; Get[mxFileName]; When the “retrieve” part is executed, I get complaints of multiple contexts and shadowing, such as x$::shdw: Symbol x$ appears in multiple contexts {Notebook$$21$649972`,Notebook$$29$735513`}; definitions in context Notebook$$21$649972` may shadow or be shadowed by other definitions. >> I understand that when I re-open the saved .nb file it gets a new context name, in this case Notebook++21+649972-, and by examining the top of the .mx file it is apparent that it is associated with another context, in this case Notebook++29$735513- which is probably the context of the notebook before closing/crashing. [[Note that in this paragraph I replaced the dollar symbol with + and the tick mark with - to prevent weird formatting within this forum post.]] Note that all of my notebook contexts are “Unique to this notebook." I have tried renaming the new context with the old context name, as in $Context="Notebook$$29$735513`” before running the “retrieve” code but none of my definitions are restored. I feel that I am close to making this work and this approach seened to work on small test notebooks. What am I doing wrong? Jerry Jerry 2015-02-05T21:54:02Z https://community.wolfram.com/groups/-/m/t/471839 Hi, I would like to know if the upgrade for Mathematica 10.0.2 home edition to 10.1 home edition is seen as a whole new version and therefor should be a paid upgrade (aprox 90 dollar). regards, Lou l van Veen 2015-04-01T20:45:15Z https://community.wolfram.com/groups/-/m/t/370999 I have a lot of different project that require data. One awesome source of data I found is: https://datamarket.azure.com I know how to get simple API data from GET but not sure how to do this Microsoft one. I looked through the tutorials and videos and none really get into the nitty gritty of pulling in API data in multiple ways. David Johnston 2014-10-17T02:10:08Z https://community.wolfram.com/groups/-/m/t/485974 Hello, I am in the middle of making a CDF for a collection of expensive calcuations and plots. I've gone with DynamicModule and have read the documentation but I've obviously missed a few things as it is not working as expected. The code below demonstrates my problem but the actual code of calcuations and plots is much, much larger. 1. The controls created by the makeControl function for the dynamic variables do not display on first execution but everything else does. That is, if you - delete the output cell, - quit and then start the kernel, - and execute the module then those controls show as the text of the commands that make them. Then executing the module a second time the controls show as the are supposed to. The plots and charts are linked to the update variable and refresh when the Run Simulation button is clicked on both the first evaluation and the second evaluation. 2. The Dynamic@Refresh keeps kicking out a Null. If I end it with a ; then none of the plots and tables update when the Run Simulation button is pressed. This seems odd that making it not display output results in it not running the code inside. Is this a bug? 3. When previewed as CDF Player I get a ton of errors from the FE' context when I click the Run Simulation button. I have SaveDefinitions -> True on the module so am not certain why this is happening. 4. When the notebook window is moved the simulation runs repeatedly. Also, when CDF Player is previewed moving the window it is in causes the simulation to repeatedly run. This only happens in the CDF Player preview until the Run Simulation button is pressed. After it is pressed moving the window does not cause the simulation to run. It always runs in the notebook when the window is moved even after pressing the Run Simulation button. It is an expensive simulation so this behaviour is very much not desired. Notebook is attached with code example that has all four issues. Edmund Robinson 2015-04-25T21:18:26Z https://community.wolfram.com/groups/-/m/t/383178 **Hello, I'm trying to discretize a very fine ring with "ImplicitRegion", but Mathematica does not let me.** in: ?x=ImplicitRegion[?0.12?^2?x^2+y^2??0.125?^2,{{x,-0.125,0.125},{y,-0.125,0.125},{z,0,1.}}] out: ImplicitRegion[0.0144?x^2+y^2?0.015625&&-0.125?x?0.125&&-0.125?y?0.125&&0?z?1.,{x,y,z}] **Answer:** DiscretizeRegion::drf: DiscretizeRegion was unable to discretize the region ImplicitRegion[<<2>>]. >> **BUT is a 3D Región, Why was it unable?.** **Equal if i use:** in: ?x=RegionDifference[Cylinder[{{0,0,0},{0,0,1}},0.125],Cylinder[{{0,0,0},{0,0,1}},0.12]] out: ImplicitRegion[0.0144?x^2+y^2?0.015625&&-0.125?x?0.125&&-0.125?y?0.125&&0?z?1.,{x,y,z}] **Answer:** DiscretizeRegion::drf: DiscretizeRegion was unable to discretize the region ImplicitRegion[<<2>>]. >> How can i do?, Thanks. Jesús. Jesús Manuel Cillero Ares 2014-11-03T19:36:16Z https://community.wolfram.com/groups/-/m/t/428854 Hi All, I have tried my best to speed up the simulation below. Could it be made more time efficient ? Please ignore the LV function for now. TFinal = 0.5; NN = 10; r = 0; dt = TFinal/NN; (*Initial Stock*) (*All the parameters should be easily extractable from the files \ available*) S0 = 1; Num = 100000; (**) Tmin = 0.01; T = Tmin; LV = Compile[{{x, _Real}}, 0.8]; (******************) ParallelEvaluate[Off[InterpolatingFunction::dmval]]; (*Initial Simulation Block*) SimPathsLV = Transpose[Reap[ Sow[ParallelTable[S0, {Num}]]; Sow[ SamplePaths2 = ParallelTable[ Nest[(a = RandomVariate[NormalDistribution[0, 1]]; #* Exp[((r - 0.5*(LV[#])^2)*dt + (LV[#])*Sqrt[dt]*a)]) &, S0, 1], {Num}]]; For[k = 0, T < TFinal, k++, T = T + dt; Sow[ SamplePaths2 = ParallelTable[ Nest[(a = RandomVariate[NormalDistribution[0, 1]]; #* Exp[((r - 0.5*(LV[#])^2)*dt + (LV[#])*Sqrt[dt]*a)]) &, SamplePaths2[[i]], 1], {i, 1, Num}]] (*Appending out iteration of the simulation*) ]][[2, 1]]] // Timing; SimPathsLV[[1]] Nabeel Butt 2015-01-26T19:53:49Z https://community.wolfram.com/groups/-/m/t/1793523 I am looking for a solution for a minor but annoying flaw in a program that I made for building a CDF for analysing the properties of accumulations of random numbers. In the CDF I can choose for several types of such accumulations through a number of radiobuttons. With each radiobutton I can make a list that contains the sum of the accummulation in question along with several parameters and quantities that I for instance need for a text above the final chart of the accumulation and some additional special properties of it. Together with each radiobutton for any accumulation with a certain probability distribution the CDF has one or more inputfields for the necessary parameters, such as mean and standard deviation for a normal distribution. My problem is the following: After pushing a radiobutton and then inserting a number in an inputfield that goes with that button, and then hitting Enter or clicking with the mouse outside of the input field, the radiobutton turns white and in order to make the number in the input field do its work I have to push this radiobutton anew. What I want is that the new situation is activated right away after entering a number in the inputfield and then pushing Enter of clicking with the mouse outside of the inputfield. I hope there is a solution for this. This is the program all the way stripped down to the relevant section: Export["Testpanel.cdf", CreateDocument[{ DynamicModule[{y, beta, center, standarddeviation, mean}, Row[{ Row[{ Dynamic[ SeedRandom[1]; RadioButton[ Dynamic[y], {" Laplace", " distribution", " ", Accumulate[ RandomVariate[LaplaceDistribution[center, beta], 1000]], 0}]], TextCell[" Laplace "], center = 0; InputField[Dynamic[center], FieldSize -> 3], beta = 1.7; InputField[Dynamic[beta], FieldSize -> 3], TextCell[" "], Dynamic[ SeedRandom[1]; RadioButton[ Dynamic[y], {" normal", " distribution", " ", Accumulate[ RandomVariate[NormalDistribution[mean, standarddeviation], 1000]], 0}]], TextCell[" Normal "], mean = 0; standarddeviation = 1; InputField[Dynamic[mean], FieldSize -> 3], InputField[Dynamic[standarddeviation], FieldSize -> 3], TextCell[" "] }], Dynamic[Show[ ListPlot[ Partition[Riffle[Range[1, 500], y[[4]][[1 ;; 500]]], 2], PlotStyle -> {PointSize[0.003], White}, Background -> Black ], ImageSize -> 500]] }] ]}]] **Additional information**: In the meantime I discovered that after putting a new number in an inputfield instead of hitting Enter or clicking outside of the inputfield and then pushing the radiobutton again one may also get desired result by right away pushing the Radiobutton 3 times. So in fact my problem may be considered as solved. Laurens Wachters 2019-09-20T12:38:22Z https://community.wolfram.com/groups/-/m/t/356128 Dear members of the group Could some one explain why the following line produces two surfaces in the same Plot in Mathematica, but the same line always produces two separated plot in Wolfram|Alpha? Plot3D[{Sin[x y], Cos[x y]}, {x, -\[Pi], \[Pi]}, {y, -\[Pi], \[Pi]}] Thanks in advance. Jesus Rico J Jesus Rico-Melgoza 2014-09-26T18:25:31Z https://community.wolfram.com/groups/-/m/t/428815 I am interested to know if there is a way I could speed up computation involving an interpolated function ( does the kernel generate an internally compiled code?) . Generally Compile works well for most types of problems not involving interpolation. In this case what is the suggested approach without using parallelization ? The relevant code is below: fi = Interpolation[Table[{i, Sin[i]}, {i, 0, 1, 0.1}]]; a1 = Table[fi[0.35], {100000}] // Timing; a2 = Table[Sin[0.35], {i, 1, 100000}] // Timing; a1[[1]] a2[[1]] Nabeel Butt 2015-01-26T18:54:55Z https://community.wolfram.com/groups/-/m/t/552479 I am working with genetic algorithm for optimization. I feel problem in crossover of binary chromosomes. I actually succeeded in making code for crossover of chromosome but now I failed to incorporate crossover probability in it. I want crossover probability of 0.85 which; in my program means, about 3 binary sets (elements) out of 18 are copies as same without cross overing. Here, I share my program which I made until now; I need incorporation of cross over probability in it. crossover[c1_List, c2_List] /; Length @ c1 == Length @ c2 := Module[{cut, c1a, c1p, c2a, c2p}, cut = RandomInteger[{2, Length @ c1 - 1}]; {c1a, c1p} = {c1[[1 ;; cut]], c1[[cut + 1 ;; -1]]}; {c2a, c2p} = {c2[[1 ;; cut]], c2[[cut + 1 ;; -1]]}; {cut, Join[c1a, c2p], Join[c2a, c1p]}]; SeedRandom[42]; genome1 = RandomInteger[1, {6, 8}] genome2 = RandomInteger[1, {6, 8}] MapThread[crossover, {genome1, genome2}] Thanks in advance. :) mamoona arshad 2015-08-24T08:28:14Z https://community.wolfram.com/groups/-/m/t/407668 Hi, One of the greatest difficulties I have with Mathematica is pairing braces, brackets, and parentheses. I am constantly forgetting one and it is quite difficult to correct this type of mistake. On the Mac, I've learned about Ctrl+. and Shift-Command B, which are helpful, but I still struggle. When I am working in RStudio, typing in my R code for statistics, if I open a bracket, a closing bracket is automatically entered. If it was a mistake to hit the bracket key, deleting the left bracket deletes both opening and closing brackets automatically. The same thing happens when you enter an opening brace or an opening parentheses, closing braces and parentheses are automatically included. A lot of folks on this website probably have a rich knowledge of the history of Mathematica, but I really wonder why Mathematica doesn't have a similar tool. Or perhaps it does and there is something I can turn on to make this happen when I am entering code? If not, is there some reason why Mathematica has never favored this procedure? David Arnold 2014-12-15T03:26:17Z https://community.wolfram.com/groups/-/m/t/247415 Hello Community, I am working with oceans of chromatographic data gathered from HPLC with DAD endpoint detection. I am currently considering performing some PARAFAC/CANDECOMP on the three-dimensional data, and wanted to hear if anyone has any experience/suggestions on how PARAFAC/CANDECOMP can be performed using Mathematica? I know of some other mathematical softwares that can do the job, but I haven't been able to find any information on that topic in Mathematica. I would prefer using Mathematica, as I have some other scripts working on the data. I have speculated on whether some "r" package could be called from Mathematica, to process the data, but I don't know if this is possible. So if anyone has some experience they can share and can point me in some direction from which the problem is easiest to tackel, I am all ears. Does not have to be applied on the same data set, as the one I am working with. Best Regards Simon P. 2014-05-05T14:34:22Z https://community.wolfram.com/groups/-/m/t/507636 Hi, I try to use NDSolve to do this partial differential equations, but the result is wrong... The source term is a Gaussian pulse as time and an exponential decay with the depth z. The result should be going to some small value at a large time, but it keeps "plat" when it goes to a large time. I attach my notebook in the attachment, thank you! ![p1][1] ![p2][2] ![p3][3] ![p4][4] ![p5][5] ![p6][6] [1]: /c/portal/getImageAttachment?filename=p1.png&userId=507361 [2]: /c/portal/getImageAttachment?filename=p2.png&userId=507361 [3]: /c/portal/getImageAttachment?filename=p3.png&userId=507361 [4]: /c/portal/getImageAttachment?filename=p4.png&userId=507361 [5]: /c/portal/getImageAttachment?filename=p5.png&userId=507361 [6]: /c/portal/getImageAttachment?filename=p6.png&userId=507361 Wit Z 2015-05-31T22:59:21Z https://community.wolfram.com/groups/-/m/t/1046546 I am using the "Water" stylesheet for a slide show that has some problems when printing the slides as PDF, etc. When using e.g. ItemNumbered cells the item numbers get cropped at the left edge. Does anybody knwo which style settings to adjust to keep the full cell visible? To clarify the issue take the following minimal slide example (StyleSheet "Water") ![enter image description here][2] Switching to Printout environment gives: ![enter image description here][3] Note how the item numbers are cut off at the left page edge. How can I change that? ---------- This is also cross-posted here: http://mathematica.stackexchange.com/questions/141186 [1]: http://mathematica.stackexchange.com/questions/141186/modify-slide-show-printout-settings [2]: http://community.wolfram.com//c/portal/getImageAttachment?filename=working.png&userId=87900 [3]: http://community.wolfram.com//c/portal/getImageAttachment?filename=printoutjpg.jpg&userId=87900 Markus Roellig 2017-03-29T08:22:12Z https://community.wolfram.com/groups/-/m/t/450989 Hello guys, I've been working on ParametricNDSolveValue with 4th order Runge-Kutta method and sometimes I received this error ParametricNDSolveValue::mxst: Maximum number of 10000 steps reached at the point x$214882$215402 == 0.9256478123350554`. InterpolatingFunction::dmval: "Input value {1.} lies outside the range of data in the interpolating function. Extrapolation will be used." FindRoot::lstol: The line search decreased the step size to within tolerance specified by AccuracyGoal and PrecisionGoal but was unable to find a sufficient decrease in the merit function. You may need more than MachinePrecision digits of working precision to meet these tolerances For the RK4 method my StepSize->1/1000, I've tried changing the PrecisionGoal and AccuracyGoal, only the point of x changes but also with the same error. This error does not occur all the time, if the I change the value of the inputs, sometimes I don't receive this error Below is the code from other threads I had post and received help from the community. prog := Module[{Twater = 300., Tnew = 0, Cwater, Dwater, Ewater, ClassicalRungeKuttaCoefficients, f, x, y, point, ans, tol = 0.001, iters = 0, iterLim = 100, prevTnew = 10^5, plotList = {}}, $MinPrecison = 50; Cwater = QuantityMagnitude[ ThermodynamicData["Water", "ThermalConductivity", {"Temperature" -> Quantity[Twater, "Kelvins"]}]]; ans = "Twinkle, twinkle, little star, How I wonder what you are. Up above the world so high, Like a diamond in the sky. Twinkle, twinkle, little star, How I wonder what you are!"; While[(Abs[prevTnew - Tnew] > tol) && (iters++ < iterLim), Dwater = (5 Cwater)/Pi; Ewater = Dwater^3 + 2*Cwater; ClassicalRungeKuttaCoefficients[4, prec_] := With[{amat = {{1/2}, {0, 1/2}, {0, 0, 1}}, bvec = {1/6, 1/3, 1/3, 1/6}, cvec = {1/2, 1/2, 1}}, N[{amat, bvec, cvec}, prec]]; f = ParametricNDSolveValue[{SetPrecision[ Derivative[1][y][x] == Piecewise[{{(y[x] + x^3 + 3 z - 120*Ewater), 0 <= x <= 1}, {(y[x] + x^2 + 2 z), 1 <= x <= 2}, {(y[x] + x + z), 2 <= x <= 3}}], 40], y[0] == 0}, y[3.], {x, 0., 3.}, z, Method -> {"ExplicitRungeKutta", "DifferenceOrder" -> 4, "Coefficients" -> ClassicalRungeKuttaCoefficients}, StartingStepSize -> 1/1000]; point = {z /. FindRoot[f[z] == 100., {z, 0.1}, Evaluated -> False], 100.}; AppendTo[plotList, point]; Print[point]; FindRoot[f[z] == 100., {z, 0.1}, Evaluated -> False]; prevTnew = Tnew; Tnew = 170 + 1.89*z /. FindRoot[f[z] == 100., {z, 1}, Evaluated -> False]; Cwater = QuantityMagnitude[ ThermodynamicData["Water", "ThermalConductivity", {"Temperature" -> Quantity[Tnew, "Kelvins"]}]];(*Note Tnew here!*) Print["Twater: ", Twater, " Tnew: ", Tnew];];(*End while*) ans = {"Tnew: ", Tnew, "Cwater: ", Cwater, "Dwater: ", Dwater, "Ewater: ", Ewater}; Print["The answer is:\n", ans];]; The question is, I have find the StepSize to 1/1000, so wouldn't ParametricNDSolveValue run the command with step size of 0.001? Why would it stop before that? NOTE: this is the example of the model, I cannot post my real model. Thai Kee Gan 2015-03-02T03:08:30Z https://community.wolfram.com/groups/-/m/t/391202 Does anybody know a quick way to get all the locations of your Facebook friends in Mathematica. It looks to me like you have to transfer the entire user data for each user and then parse out the location info yourself. And, does anybody have access to the code that went with Stephen's big blog post about all the analysis one can do of Facebook data. Thanks Mark Lawton 2014-11-17T06:02:38Z https://community.wolfram.com/groups/-/m/t/471104 Hello, Although I submitted the same question a couple of days ago here, but I am still trying to solve the 1-dim acoustic wave equation with two different media. Actually, though this equation, I want to know how much the acoustic pulse is reflected and transmitted at the interface. Could you please help me or can give some comments ? In the following code, I used the two continuity conditions of the acoustic wave at the interface of media, which are pressure and displacement continuity conditions. Thank you very much in advance. Remove["Global`*"]; L = 10.0; T = 3.0; (* L : boundary, T : time *) \[Rho]1 = 5; \[Rho]2 = 4; (* mass density of each layer *) v1 = 5; v2 = 4; (* speed of sound of each layer *) (* For continuity conditions at interface, Pressure : \[Rho]1 v1^2 \ (D[u1[x,t],x]/.x->0)== \[Rho]2 v2^2 (D[u2[x,t],x]/.x->0), \ Displacement : u1[0,t]==u2[0,t] *) Sol = NDSolve[{D[u1[x, t], t, t] == v1^2 D[u1[x, t], x, x], D[u2[x, t], t, t] == v2^2 D[u2[x, t], x, x], (D[u1[x, t], x] /. x -> L) == 0, (D[u2[x, t], x] /. x -> -L) == 0, \[Rho]1 v1^2 (D[u1[x, t], x] /. x -> 0) == \[Rho]2 v2^2 (D[u2[x, t], x] /. x -> 0), (D[ u1[x, t], t] /. t -> -1) == 0, (D[u2[x, t], t] /. t -> -1) == 0, u1[x, -1] == Exp[-20 (x - L/2)^2], u2[x, -1] == 0}, {u1, u2}, {x, -L, L}, {t, -1, T}, MaxSteps -> Infinity, Method -> {"MethodOfLines", "SpatialDiscretization" -> {"TensorProductGrid"}}][[1]] Plot3D[u1[x, t] /. Sol, {x, -L, L}, {t, -1, T}, PlotRange -> All] hwoarang Polar 2015-03-31T19:14:23Z https://community.wolfram.com/groups/-/m/t/523344 Attached is some simple-minded code that explores lower-order order logical independence of the boolean functions of two and three variables. Eventually, I'm looking to generalize it to n variables. For the moment I'm just trying to understand if there's extant work or code out there that is applicable. Thank you, -- Mark Mark Tuttle 2015-07-06T18:40:19Z https://community.wolfram.com/groups/-/m/t/1818557 I can connect to an external MQTT broker with the MQTTLink` library. Here below an example using the Mosquito.org testing service: Get@"MQTTLink`" imAclientForExternal = CreateClient[]; ConnectClient[imAclientForExternal, "test.mosquitto.org:1883"]; TopicSubscribe[imAclientForExternal, "wolframTest", "MessageReceivedFunction" :> (Print[ ByteArrayToString[#3["Data"]]] &)]; TopicPublish[imAclientForExternal, "wolframTest" -> "my personal message"]; TopicUnsubscribe[imAclientForExternal, "wolframTest"] But since this is not a documented library, I was wondering if it is possible, and how, to do exactly the same with the Channel framework. Pedro Fonseca 2019-11-03T17:33:20Z