0
votes
0answers
7 views

Computation of Hankel Transform Rainer example

I found Rainer's answer to be perfect. However I would like to know if he could upload his code for calculating the propagation of optical fields (for example, to reproduce Fig.3 from the reference he ...
0
votes
0answers
6 views

How to copy Coordinates of “Get Coordinates” in Figure?

I am trying to reproduce the answer here about Recovering data points from an image. I click the figure and press "Get Coordinates". I would like to copy the four coordinates by CTRL-C and then paste ...
0
votes
0answers
7 views

Théorie de Fourier in Sontag`s book

I was reading Sontag`s In America and she mentions: "La théorie de Fourier sur les douze passions radicales.." What is this theorem about?
0
votes
0answers
7 views

ParallelDo does not work, when using variables from other parts of the script

I have a script doing a large amount of calculations with very big matrices that takes so long; so, I want to parallelize pieces of the script to be executed on multiple kernels. For instance, the ...
2
votes
0answers
14 views

benchmark of Mathematica's FEM?

Does anyone have any numbers on how mathematica compares to other commercial (eg ANSYS) or free FEM softwares (eg. FreeFEM++, FEniCS, elmer)? If this is too vague say solving the diffusion equation in ...
0
votes
0answers
12 views

Bouncing a disk off a line

I have been working with this concept and have not been able to accomplish it yet. I am trying to have the disk slide to the determined location but if it hits the line it bounces off at the ...
0
votes
0answers
2 views

Complex number simplifications

My Mathematica notebook is not simplifying some expressions which do look trivial. I mean that one of my outputs contains: ...
0
votes
0answers
10 views

Copy xAct expression to LaTeX

How can I copy an xAct expression to LaTex? Using the usual command TeXForm[] gives the xAct structure, I would like to get the printed form. For example $$ \text{TeXForm}[\nabla_a\phi\nabla^a\phi] ...
1
vote
1answer
35 views
1
vote
2answers
20 views

How to round all the numbers in a function?

I have a complicated function that is a combination of floating-point numbers and variables. I want all the numbers rounded off, but I have no clue how to do this. For example I would want ...
0
votes
0answers
12 views

Extract stiffness matrix from NDSolve

I am solving a set of ODE equations with NDSolve with more than 25 equations. I was wondering is there any way Mathematica gives me the mass and stiffness matrices?
0
votes
0answers
20 views

How to attach a notebook to a question? [migrated]

As I have posted a number of times, I am still learning how to do things here. I was wondering if someone could help me to figure out how to attach a notebook file to a question. Thanks Tarynn
2
votes
2answers
17 views

Numerically solving coupled ODE's with a parameter as initial condition

i'm currently trying to numerically solve a set of coupled ODE's to obtain the functions p(r), h(r) and m(r) in the range of r1 <= r <= r2 with initial conditions m(r1)=a=const and ...
1
vote
0answers
13 views

Text in Popupmenu that cannot be chosen

Is it possible to make a popupmenu where there is text inserted into the options which you cannot choose. For instance: a popup menu with animals devided into two categories. Birds: duck, eagle, ...
6
votes
0answers
41 views

Can Mathematica solve functional equations with nested variable?

First, inline free form input can solve these equations: But it seems no native Mathematica function can solve these, there is even an error page for equations of this form (nestdv). Now my ...
3
votes
0answers
14 views

Reading Cells or Boxes expression by expresson

Let's say we have a cell: (*newline*) (*newline*) Plot[ x, {x, 0, 1} ] (*newline*) Plot[x, {x, 0, 2}] How to read it expression by expression? ...
1
vote
1answer
23 views

Pareto optimal fronts using internal function?

Reading this question: How do I estimate the Pareto front in my multiobjective optimization problem? I found @Daniel Lichtbau's interesting answer. Yet I don't know how such an "internal function" ...
3
votes
3answers
209 views

Simplify big numbers

How can I simplify big exponents like $10^{45}$ in an expression like this: Simplify[Sqrt[3.1 10^45 + x 10^47]/(1 10^22)] It works well if all numbers are ...
3
votes
1answer
32 views

How can I choose the coeffcients so that the givent system of equations has four integer solutions?

Consider the system of equations with unknown are $(x,y)$. $$\begin{cases} a_1x^2+b_1y^2 + c_1xy+d_1x + e_1y+f_1=0,\\ a_2x^2+b_2y^2 + c_2xy+d_2x + e_2y+f_2=0. \end{cases}$$ I want to find the ...
1
vote
1answer
43 views

Finding roots of Bessel function $y=3J_1(x)+xJ_1'(x)$ is returning inaccurate roots. Not Kernel bug [on hold]

I can't figure out why Mathematica is returning the incorrect roots. The first five should be 2.9496,5.84113,8.87273,11,9561, and 15.0624 according to my textbook. ...
0
votes
1answer
31 views

Plot confidence interval around curve

I need to plot a confidence band around a curve in Mathematica, similarly to what done with r in the image below (from here). What is the best way to do it? My ...
0
votes
1answer
15 views

Using an interpolating solution of NDSolve into an algebraic expression

I would like to use the interpolating solution of NDSolve into an algebraic expression without creating a system of a differential equation and algebraic equation. The example is the following: ...
0
votes
1answer
14 views

Is it the correct syntax with TransformedDistribution?

I define a function as f[x_] := ...;which is in fact the PDF of a random variable $X$. The PDF if given by $f_X(x)$. Let $Y$ is a random variable, which is the ...
3
votes
4answers
119 views

Is there a way to PrependTo or AppendTo while flattening the result in the same step?

arr = {1, 2, 3}; PrependTo[arr, {a, b}] (* {{a, b}, 1, 2, 3} *) But, I want (* {a, b, 1, 2, 3} *) I know I can use ...
2
votes
2answers
56 views

Raspberry Pi Temperature and Performance

I just got a raspberry pi 3 and want to get a rough idea of the max temp I might reach while doing intensive calculations. What would you suggest I calculate in mathematica to get the pi hot? ...
4
votes
0answers
37 views

Macro functions in GeneralUtilities?

Questions have been asked about the Macros package before, but I'm interested if anyone has some examples of using the macro related functions in GeneralUtilities: ...
3
votes
0answers
39 views

How to efficiently find only the rational roots of a rational complex polynomial?

I need to find all the rational roots of a bunch of high-order polynomials with rational complex coefficients. Is there an efficient way to do this? My best effort on an example polynomial: ...
5
votes
0answers
41 views

Using Cases to pick out entries of a SparseArray

I'm trying to use a SparseArray for some large homological algebra calculations. I'd like to find indices of a SparseArray ...
3
votes
1answer
67 views

Does Solve[] find ALL the exact roots of rational polynomials?

Does Solve[] find ALL the exact roots of rational polynomials? I've done a bunch of tests where I created an expression with some analytic roots, and Solve[] always found them all. But is the ...
0
votes
0answers
51 views

Why Integral does not converge?

I am trying to solve for $\Omega$ this nonlinear integral equation : $$1+\dfrac{z}{k^2}-\dfrac{z^2}{K_2(z)} \dfrac{\Omega}{k^3} \displaystyle\int_{1}^{\infty} \gamma^2\, \text{ArcTanh} ...
4
votes
1answer
36 views

CForm not getting exp(), pow, log() functions

I'm performing derivatives in Mathematica and I want to use them in a C code. For that, I'm using CForm as for example in this expression: ...
0
votes
0answers
30 views

function as argument in a package

I would like to customize the function DensityPlot and use it in a package as a function called MyDensityPlot: The functions ...
0
votes
0answers
35 views

How to speed up NDSolve?

I have a program where I need to iterate NDSolve thousands of times for different configurations of a diffusion problem. The thing is, I only need about 3 digits of accuracy. I looked thru previous ...
2
votes
1answer
67 views

Replace pattern for exponentials

Ultimately, I want to replace every Exp[(const) w[i,j]] to T[i,j] and Exp[-(const) w[i,j]] to 1/T[i,j] in the following expression ...
0
votes
0answers
41 views

Lyapunov exponent of non-autonomous differential equation

I am trying to calculate the Lyapunov exponent for a non-autonomous system using M Sandri code, but it always shows me error "infinite expression 1/0 encountered". Does anyone know about this? Mr. ...
-1
votes
1answer
33 views

Maclaurin Series Help [on hold]

My problem is to numerically approximate the series (1 - Cos[x])/x over the interval [0,1]. I typed it into Mathematica as so: ...
0
votes
0answers
39 views

All Graphics3D commands crash

Recently updated from Mathematica 8.0 to 10.2 running on Windows 7 (8.0 was uninstalled before installing 10.2). Anytime a 3d graphics is rendered, the first rendering in a notebook is completely ...
0
votes
0answers
27 views

NDSolve kernel crash, affected by variable naming

The following isolated example cannot be further simplified much to reproduce a crash. I've already submitted the issue to TechSupport, but it seems this is not an easily reproducible case, so I'm ...
-1
votes
0answers
40 views

Pumping Lemma - non regular [on hold]

Can everyone help me to show that: the language L = {a,b}* \ {a^m b^2 m a^n | m,n >= 0} is not regular. I don't know what is the meaning for the proof.
4
votes
1answer
91 views
1
vote
1answer
43 views

Input in Manipulate

Plot[Evaluate[ Input["Please input a function of x to plot with one parameter \ \[Alpha] to manipulate"]], {x, 0, 1}] This work without doubt. But ...
2
votes
0answers
32 views

Using TraditionalForm to express equations

I have a notebook in which a couple of partial derivatives are calculated. At the time of publishing this notebook, I'd like to make the resulting equations look the way they would in standard ...
0
votes
0answers
25 views

Bezier curves function in mathematica [on hold]

I need help urgently, for next monday I need to write the name ALAN using BEZIER CURVES programming it on mathematica, but I'm not allowed to use the bezier curves function that mathematica already ...
7
votes
1answer
299 views

Is there a way to make a bihistogram plot?

Is there a way of making a bihistogram plot in mathematica? There is a reference to it at http://mathworld.wolfram.com/Bihistogram.html but no suggestions as to how to do it.
2
votes
1answer
51 views

how to apply Alternatives command to delete cases from a list?

I have two lists let say listF = {{7, 2}, {2, 6}, {8, 1}, {1, 7}, {11, 8}, {6, 11}}; and ...
0
votes
2answers
118 views

Dynamical system problem x(t+1) = Ax(t)

I have a problem that have been trying to solve but it's not going so good. I would like some guidelines on how to work myself around this problem: Two neighboring countries spy on each other and ...
0
votes
0answers
52 views

How to calculate the slope in a data set plotted in ListPlot?

I am working with a large set of data that follows an exponential behaviour. My challenge is to create a function in Mathematica with these objectives: Retrieve the information from an Excel File ...
1
vote
1answer
48 views
0
votes
0answers
46 views

Animation of the wavefield

I was trying to animate contour plot as a function of time. Basically, it is contour plot of wavefield that is changing throughout the time. Here is my attempt: ...
0
votes
1answer
51 views

NIntegrate[] Gamma Function

Gamma Function is known to be : Source first i plot the function z = 1; f[t_] := (t^(z - 1))/Exp[-t]; gamma = Plot[Gamma[g], {g, 1.0, 5.0}] then, i ...

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