All Questions

0
votes
1answer
98 views

How to use Mathematica's Moment Generating Function?

Given the following p.d.f., which is the p.d.f. of the ratio between a complex Gaussian and a Chi-squared RVs: \begin{equation*} f_U(u)=\exp\Big\{{-\frac{1}{4 u^2}}\Big\} \,\frac{\left(8 n u^2-1\...
0
votes
1answer
56 views

Taking derivative of general order

How can I directly evaluate the following derivative? $$ \frac{\partial ^n}{\partial x^n}\bigg[\sum_{k=1}^{m} (m-k)! (ax+b)^k\bigg] = \sum_{k=1}^{m} (m-k)! \bigg[\frac{k!}{(k-n)!}a^n (ax+b)^{...
5
votes
1answer
39 views

How to make Orthogonalize simplify each new vector before using it to orthogonalize the next one?

I'm trying to construct a set of orthogonal polynomials, starting from a specially-prepared initial polynomials: ...
1
vote
2answers
36 views

Removing axes numbering

I have the following example where I want to see the numbering only of the left y axis and the bottom x axis. The FrameTicksshould be the same for the both x axes ...
-3
votes
0answers
50 views

How to design and deal with repeating decimals? [on hold]

Repeating decimals could be represented by fractions. Given $ \huge{\frac{1}{3}=0.33333\overset{!}{3}}\tag{1} $ if multiply $3$ on both sides,is this step wrong?...
2
votes
0answers
71 views

Get matching types for pattern

I want to take a pattern and get a set of matching types. The set of types does not need to be complete, but it needs to satisfy, say, 90% of the cases. Here's is a (definitely not complete) set of ...
6
votes
7answers
934 views

How to display very small numbers in Mathematica?

I am trying to evaluate the function: $$f(x) = \cos(x) - \mathrm{e}^{-2.7 x}$$ at $x = 1.7 \times 10^{-25}$ and Mathematica keeps returning '0.' How do I evaluate the expression in a better way?
6
votes
1answer
107 views

How can I make a webpage where people can evaluate my code?

Inspired by JS Fiddle I'd like a way to write a little snippet of Mathematica code and then get it to show up on a website so people can play with it. I know I could put it into a cloud notebook, but ...
1
vote
2answers
51 views

Why does Sum[Length[Divisors[a]], {a, 1 ,x}] return x?

I am summing the number of divisors and I am getting the strange answer below even where there is no input to this function. ...
0
votes
1answer
52 views

Why am I getting “Erfi” for the Integral of E^x^2? [on hold]

Grandson & I have been working our way through the calculus of exponential functions. When we try to integrate E to the x^2,...
0
votes
0answers
20 views

Multifractality - Wolfram Code [duplicate]

In order to descrive the multifractal behaviour of a set, Baumann provides a code based on the functions Dq and Tau, given below. ...
2
votes
0answers
23 views

How export graphic with embedded URL hyperlink

Suppose I first create a graphic, e.g.: data = Min[#, 100] & /@ RandomVariate[NormalDistribution[70, 10], 60]; graf = Histogram[data, 10, "ProbabilityDensity"] ...
0
votes
0answers
71 views

Solving a differo-integral equation [duplicate]

I've the following equation for x(t): $$x'(t)\cdot\text{a}+\text{b}\cdot\frac{x'(t)}{x(t)+\text{c}}+\frac{\partial}{\partial t}\left\{\int_0^tx(\tau)\cdot\mathcal{...
1
vote
1answer
87 views

Rotation in physics

I have a mathematica problem in theoretical physics: There is a rotation axis $\vec{n}$ with $|\vec{n}|=1$. Each other vector $\vec{v}$ can be seperated in relation to $\vec{n}$ in a parallel part ...
3
votes
2answers
82 views

Is it possible or how to extract message string from binarized list?

Given message copied from Silvia's profile page, a binarized list could be found bellow. ...
0
votes
0answers
42 views

Trying to select data in a csv based on month

I have a csv file that has the measured data (conc), where it was collected (z) and date. I'm trying to select data based on the month it was collected in so I can plot them separately and compare. I ...
1
vote
0answers
45 views

Function returned from module doesn't work [on hold]

I have a sequence of steps that work in the main notebook: ...
1
vote
0answers
15 views

How would I obtain error information on a $Failed GeoElevationData?

The following code returns an error: GeoElevationData: with no description of the error. I think this error may be because I am asking for elevation data that is ...
3
votes
2answers
43 views

Get complete graph from set of vertices?

There is a function in Mathematica called CompleteGraph which takes a number and makes a complete graph with that number of vertices: ...
0
votes
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. ...
4
votes
3answers
124 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"}}; ...
6
votes
3answers
312 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 ...
3
votes
2answers
58 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 ...
0
votes
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 ...
4
votes
1answer
55 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: ...
0
votes
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 ...
0
votes
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 ...
4
votes
0answers
129 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 ...
2
votes
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 ...
1
vote
1answer
32 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 ...
0
votes
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. ...
2
votes
1answer
54 views

Definition of WignerD function?

On Wikipedia, elements of Wigner's D-matrix are defined as $$D_{m'm}^{j}(\alpha,\beta,\gamma)=\langle jm'|e^{-i\alpha J_z}e^{-i\beta J_y}e^{-i\gamma J_z}|jm\rangle=e^{-im'\alpha}d_{m'm}^j (\beta)e^{-...
2
votes
3answers
85 views

Two data sets superposed using two different axes styles

I saw the answer here, but I don't see the right axes labels in Mathematica 11.3. I have two data sets: ...
3
votes
2answers
55 views

Adding custom Mesh on top of existing Plot3D Mesh

I want to add custom Mesh lines onto a Plot3D, with different MeshStyle than Mesh lines which already exist. As a MWE, starting with a meshed plot ...
1
vote
1answer
67 views

How to distribute rules?

For example i want to have following equation : Det[A B C]=Det[A] Det[B] Det[C] What is the simplest way to distribute automatically?
8
votes
2answers
67 views

How to show Plots or Graphics in mini MMA HTTP Server?

I learned some codes to make a mini HTTP server in MMA way here. ...
2
votes
1answer
80 views

Using DSolve to solve an integral equation

I've the following integral (or DE) that I need to solve (for $x(t)$ and all the constants are known, real and positive): $$k\cdot\theta\left(t-m\right)+(n-k)\cdot\theta\left(t-v\right)=$$ $$x(t)\...
1
vote
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 ...
2
votes
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 ...
0
votes
2answers
63 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 ...
-2
votes
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 ...
1
vote
1answer
32 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 ...
0
votes
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 ...
17
votes
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 ...
1
vote
1answer
50 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 ...
10
votes
4answers
671 views
0
votes
2answers
49 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 ...
0
votes
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 ...
0
votes
0answers
19 views

Set Windows Status Area [on hold]

How to set content of status bar in current notebook file??? ...
2
votes
1answer
21 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 ...

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