All Questions

57,893 questions
1answer
65 views

DeleteDuplicates not working for a list in main program [on hold]

I have a list of dimension $50 \times 1$. The list has some duplicates, I used DeleteDuplicates to delete repeated elements, which however seems not working. ...
3answers
130 views

How to Partition rest rows by the first row?

Given a list lst = {{{"1","2","3"},{"4","5"},{"6","7","8","9"}}, { "A","B","C","D","E","F","G","H","I"}, { "9","8","7","6","5","4","3","2","1"}}; ...
3answers
319 views

How to concatenate list of integers into a single number

Is there a way to concatenate the elements of a list into ONE number? For example, if there is a list L={13,5,8,0}, then I am looking for a way to append ...
2answers
60 views

Importing an Excel file as a structured dataset

I need to import an Excel file as a dataset with row and column headers, and the following option using "Dataset" does not work. However, I can import the Excel file using "Data" option as a list ...
0answers
47 views

Are the following Mathematica codes correct for solving wave equation PDE? [duplicate]

I wanna solve the following PDE of wave equation using Mathematica. $u_{tt}=u_{xx}$ $0<x<\pi , t>0$ Initial Conditions: $\begin{cases}u(x,0)=sin(x) \\u_{t}(x,0)=1\end{cases}$ Boundary ...
1answer
56 views

When using Mathematica Online, where are exported files saved?

I would like to 3D print some Mathematica-generated polyhedra, but I can't figure out how to download the files generated from the 'Export' command. For example: ...
2answers
31 views

ParametricPlot table of complex functions in several graphs

Assume that I have a table of complex functions like Clear[p] Clear[M] M = 10; G = Table[Sin[i p] + p I, {i, M}] I want to ParametricPlot them in graphs, each ...
0answers
33 views

OpenCL for symbolic matrix manipulations [on hold]

I want to calculate a matrix multiplication of matrices with a size of 500 for example, but all elements are symbolic. Since it is a bit slow with a normal way, and gets slower and slower with ...
0answers
132 views

When is the next release? [on hold]

I've been looking into buying a student version of Mathematica but saw the latest release was almost a year ago. The previous release cycle looked like it was every several months or so. I run Ubuntu ...
0answers
30 views

How to use DirichletCondition with DSolve and not just NDSolveValue?

I know one can use Region and DirichletCondition with NDSolveValue. But I do not know why it ...
1answer
34 views

Precalculating ThreeJSymbols to make my program faster

Does anybody have an idea what is the best way to pre-calculate the ThreeJSymbols in order to use them in a loop? (I want to make my program work faster that is why ...
0answers
24 views

A function to create a Symmetric Positive Definite Matrix, from any matrix. Why doesn't it work? [on hold]

I've created the following function with the purpose such that, given any square matrix, it should return the closest(system precision dependent) symmetric positive definite matrix. ...
1answer
59 views

0answers
33 views

Clustering different kernel versions

After a good bit of trial and error I have managed to cluster together two OS X machines. The master is running Mathematica 9.0 and the secondary 11.0. All was well and good, the remote command being ...
1answer
30 views

Using OverBarred variables

Mathematica does not seem to treat variables as a unit. Consider the following: rule = a -> Function[{x}, OverBar[a][x]] test = a[x] /. rule; test /. rule It ...
2answers
65 views

When computation takes a long time, how to find out if this is normal or if my script contains an error?

I study mechanical engineering and I' working on my first bigger project on Mathematica right now. It's a multibody problem that leads to a system of 4 large equations I'm supposed to solve ...
2answers
58 views

Solving a 2nd-order nonlinear differential equation [on hold]

My equation is [{x[t]*x'[t])'-(F/m)+(b/m)*x(t)*x'(t)==0},x(0)=0,x'(0)=0] It is a form of Newtons momentum equation, but I am having a lot of trouble solving this ...
1answer
34 views

Selecting from a matrix according to elements of a column — efficiency and speed?

I need to select all elements from matrix M that have in their 3rd column elements from some given list L (3rd column and L are real numbers). I have written the most obvious (to me) command to select ...
0answers
33 views

Errors while installing MatLink

I'm new to MatLink, I spent the last couple of hours trying to install Matlink but I did not succeed. When running Needs["MATLink`"] OpenMATLAB[] in ...
5answers
1k views

Sisyphus Random Walk

A Sisyphus Random Walk evolves as follows: With probability (r) you advance the position of the walker by +1. With probability (1-r) the walker resets at x0 = 0. To simulate the probability of reset ...
1answer
51 views

Singularities forming on boundary while solving system of pde's

This is a follow up of a previous question I asked regarding solving a system of coupled, non-linear partial differential equations, 2D spatially + time. The equations (shown below) model a magnetic ...
4answers
679 views

Set every element to zero in matrix unless it's 1 or 1/2

I have the following code: ...
2answers
50 views

How to define mixtures of random variables?

I am confused by the behavior of MixtureDistribution, even though that sounds like what I would need. Let's say I want to get a parametric solution for the ...
3answers
42 views

How to get the Roots of nonlinear equations

How to get the Roots of nonlinear equations. nu=326.531 Plot[(I*m1)*Tanh[I*m1] - nu, {m1, -1, 30}] How to get the first ten positive roots and i have tried ...
0answers
20 views

Set Windows Status Area [on hold]

How to set content of status bar in current notebook file??? ...
1answer
22 views

Specify input ports with NetGraph for network within a network

I have a network with two input ports ("a" and "b"). I want to use this net within a bigger network. The problem is that I cannot find a syntax to specify to which input port the previous layers of ...
0answers
12 views

Incremental write [duplicate]

If I have two loop i & j, and I need record time and value of i, j incrementally during each round, how to modify the ...
0answers
22 views

Can FrontEndTokenExecute[“Close”] work without a pop-up window?

I wanted to make the notebook automatically be saved and closed after an evaluation of all cells. So, I found a way to add at the end of the code: ...
0answers
75 views

Laplace equation for a trapezoidal domain

I want to solve Laplace equation over a Isosceles trapezoidal domain. I need an analytical solution . would you please guide me writing the code in mathematica. how to add the boundary conditions ...
0answers
15 views

Correction terms in the asymptotics of hypergeometric function

I am interested in obtaining the asymptotic expansion of $r(\rho)$ $($which is the inverse of $\rho$ below$)$, \rho=\frac{2b}{1-q}\left(1-\left(\frac br\right)^{1-q}\right)^{1/2}\left(_2F_1\left(\...
0answers
25 views

Why does't 'Abort evaluation' properly work when NotebookEvaluate is executed

The following procedure can be easily aborted using Evaluation > Abort Evaluation menu item: Do[j + k, {j, 1, 10000}, {k, 1, 10000}] But it is not possible if <...
0answers
34 views

Why does 0*Hold[Infinity] evaluate to 0? [on hold]

The title says it: Why does 0*Hold[Infinity] evaluate to 0. I am confused by such behavior, it almost seems like a bug. Could ...
1answer
303 views

Parallele Computing - 2 vs. 4 processor speed

I am evaluating a code which ends with Table having ParallelEvaluate of a function XXXX[phi, theta, si]. For a grid of 225 ...
2answers
100 views

Display Short Form of Large Matrix

Is there a way to display matrices in a shorter form similar to Short or Shallow? I find that I very often want to inspect the ...
3answers
411 views

Generate this sequence more efficiently

Is there a more effecient way to generate the sequence shown below. ...
2answers
30 views

How do you change from Traditional form to Input form?

I have something like this: Hold[TraditionalForm[1/2 + x^2]] And wish to change it to Input form with the use of code (that is, without clicking Cell > Convert ...
2answers
32 views

How can I get LanguagesFractions data in different years?

I want to do that. But it failed. May I change my code? Or Where can I get these data?
1answer
46 views

Where can I get these data?

Look at this, I want to find such data, but I found Wolfram doesn't have. May I use other code?
1answer
35 views

RegionPlot evaluating NIntegrate before assigning variable values and resulting in non-numerical integrands [duplicate]

I am trying to find the regions where the integral of a function a function is larger than a certain quantity using RegionPlot. For simplicity's sake, let's say the intergal I am looking to plot is is ...
1answer
56 views

Using TeXForms as vertices of a Graph

I have a set of equations written in TeX that I want to use as vertices of a graph, with edge labels showing how the equations are connected. I read the equations in from a file, then replace any ...
0answers
47 views

Benefits of using the high level entity framework over raw SQL

Has anyone that has used both SQL particularly TSQL used in Microsoft SQL Server and Wolfram Database integration into its Entity framework, provide some particular examples where the high level ...
0answers
18 views

Is it possible to send cookies to ExternalEvaluate[“WebDriver-Chrome”]

I'm wondering if it's possible to send cookies with an ExternalEvaluate command to WebDriver-Chrome. I am attempting to grab some data from a page that requires me to be logged in. Additionally, the ...
2answers
84 views

Validating a solution for a differential equation with DiracDelta

For the following differential equation $\displaystyle-\frac{\partial ^2\phi2 (x)}{\partial x^2}+\lambda ~[\phi2 (x)]^3-\mu ^2~\phi2 (x)=\phi2(x)~\delta(x)$ ...
2answers
59 views

StartOfLine and EndOfLine not working well inside Shortest

Suppose that I want to replace lines containing "b" with a new "XXX" line. This works as expected with regular expressions: ...
4answers
300 views

What is wrong with my approach to solving a heat transfer PDE?

I wanna solve the following heat transfer PDE using Mathematica. $\qquad u_{xx}=u_{t}$ with following conditions: \$\qquad \begin{cases}u(x,0)=sin(x) &0<x<\pi &,t>0\\u_{x}(0,t)=1\\...

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