All Questions

4
votes
1answer
60 views

Precision control of double integral with $i\epsilon$ prescription

I have the following double integral: \begin{equation} F[\epsilon,\Omega,\sigma] = \iint_{\mathbb{R}^2}\frac{e^{-t^2/2\sigma^2}e^{-T^2/2\sigma^2}}{(t-T-i\epsilon)^2}e^{-i\Omega(t-T)}\,dt\,dT\,. \end{...
0
votes
0answers
39 views

Nonlinear Model Fit Returning The Same Values For Different Data [closed]

I am trying to use the NonLinearModelFit Function but the outputs for all my data tables are the same. For example DATASD1 and DATA1SD3 are getting the same output for the parameter table and the ...
2
votes
1answer
46 views

The Text in GeoMarker

In continuation the topics 1 and 2: I had the map "EKB" and I needed to mark some objects. Just for example: AES= TECgas= <...
1
vote
2answers
36 views

Changing values in a column of a Dataset using a Do loop

I'm trying to use "Do" to change the entries in a column of a dataset using two adjacent columns. When I simply assign i and execute the lin for each value of i, it works but when I enclose it in Do, ...
2
votes
1answer
92 views

Deleting missing values from a dataset

I wanted to create a dataset of all UFO sightings in April of 2018. The AssociationThread doesn't want to work, because some of the entries are missing value, what ...
3
votes
1answer
108 views

How to specify non-reflective boundary conditions when NDSolving two coupled first order PDEs?

Due to a lack of fruitful answers after 3 days, this question has been reformulated in a more direct way compared to its first version. Consider the telegraph equation problem expressed as a system ...
-3
votes
0answers
40 views

How can I take the derivative wrt to qx-px? [closed]

I HAVE TO TAKE A DERIVATIVE WRT TO qx-px d/d(qx-px) ie: d/d(qx-px) F(qx-px, py, T) but Mathematica will not allow this even if I try to "trick it " by defining rx=qx-px ANY IDEA HOW i MIGHT TAKE ...
2
votes
0answers
26 views

BinarySearch Built-in and BinarySearch1 Self defined help [closed]

I am trying to create my own binary search to compare with the built-in function. I have referenced the docs, but the output is not correct and implies an issue. Please help with my function syntax ...
0
votes
0answers
30 views

Plotting a point beneath the surface of a sphere [on hold]

I'm trying to represent a point beneath the surface of the earth. I can plot coordinates based on latitude and longitude to get a point directly above where it's supposed to be, but now I need the ...
6
votes
0answers
56 views

Direction of NeumannValue on boundary

When solving partial differential equations NeumannValue is used to specify the flux across the boundary. For normal fluxes the detailed notes state They appear on the boundary ∂Ω of the region Ω ...
5
votes
2answers
59 views

Giving Plot options defined outside of the Plot expression

How can I give Plot formating expressions on a separate line just like ListPlot? When I use the following code with ...
0
votes
0answers
28 views

How to resize an input image to make its dimensions [closed]

When using the ImageTransformation command I would like for the input image to be of equal dimensions (as if the image is a square), how could I do this if the ...
1
vote
1answer
24 views

Error NetTrain::invencin: Invalid input when training a neural network [closed]

I've build a Deep neural network with various variables: ...
0
votes
0answers
47 views

Looking for integer solutions to an equation [closed]

I want to have code, where I can solve the following equation for whole numbers: $$x^3+y^3+z^3=33\tag1$$ Where $a,y,z$ and $a$ are whole real (positive and negative) numbers. And I want to give ...
2
votes
1answer
41 views

Plot shows up as blank output line

Let me start by saying this is NOT one of a thousand duplicates of the function not showing up on the plot. Mathematica has been working fine for the last 2 years, and then all of a sudden, ...
10
votes
2answers
94 views

ToElementMesh of Region with Hole

When I try to mesh the following region it fails. Why? Is there a workaround? ...
0
votes
1answer
34 views

Problem with {table values} when plotting

I have a Piecewise and Nintegrate both defined with NumericQ. The NIntegrate part of the Piecewise operates when first inserted into a working program, but not when called from inside a table. Their ...
0
votes
1answer
48 views

I am trying to solve these Chemotaxis Equations but I can't seem to make it work

I am trying to solve a a pair of coupled partial differential equations but it doesn't seem to work. I am getting the error 'Length of the derivative order is not u1[t,x]the same as the number of ...
0
votes
0answers
46 views

Problem with Z scale density plot color

I have a problem with my Z scale color... I would like to saturate the colors in order to see better the white ring... When I am doing the next line code ...
-1
votes
0answers
64 views

Analytic solution for two coupled Partial Differential Equations using DSolve [closed]

I am looking for an analytic solution to the following two coupled equations for $v(x,t)$ and $u(x,t)$: $$\frac{\partial v}{\partial x}=-m \frac{\partial u}{\partial t}$$ $$\frac{\partial u}{\partial ...
0
votes
0answers
64 views

Solve a system of coupled partial differential equations in 2D

I am new at Mathematica and I am trying to solve this system of coupled partial differential equations in 2D in cylindrical coordinates, where the model is axysimmetric, around the z axis. $\frac{1}...
0
votes
3answers
80 views

How can I join several plots a single figure using a Table?

It is possible to joint different kind of plot using a Table, The idea is to have a single plot. I have been trying using Show function y. But I can not get it. So It is possible also to add ...
1
vote
0answers
34 views

Open all documentations/help pages in a single window [on hold]

1 Anyone else face this issue of Left and Right sides clipped in the Documentation center? At 100%, 75% and 50% as below 2 How can I set the documentations/help_pages to open in the same Wolfram ...
0
votes
0answers
4 views

Solving a area problem in a different way gives different solutions [migrated]

today I was confronted with this little area problem from this video: https://www.youtube.com/watch?v=BgrWHOocYZA So I gave it a try and came up with a solution. But after comparing the solution with ...
0
votes
1answer
21 views

Constant term of Laurent polynomial in many variables

What is the quickest way to extract the constant term from a Laurent polynomial in two variables? For example $x+1 +x^{-2}y+x/y$ has constant term $+1$.
2
votes
0answers
33 views

Is there a API to scrape WhatsApp?

Is there an API to scrape WhatsApp messages into Mathematica? Either doing it directly in Wolfram Language or using some python API and WL's ExternalEvaluate. All ...
2
votes
0answers
29 views

Reduce returns false on equation solvable by LInearSolve

I was looking for general solutions of an equation I already solved for specific values with LinearSolve, but using Reduce returned False. Here's the code: ...
3
votes
1answer
38 views

Extract plot from an image with diffused lines

I found an amazing question on how to obtain a data set from an existing plot, which detailed the process very nicely. Recreated the same steps on my end but it's not working, I am assuming because ...
5
votes
1answer
35 views

Stylesheets & Wolfram Cloud

Can one use a custom stylesheet in Wolfram Cloud? I didn't see such an option but maybe there's a non-obvious way.
7
votes
1answer
165 views

Programmatically creating a notebook containing plots for PDF export

In order to save computation results, I want to programmatically create some MMA notebooks and export them as PDF files. It works fine for text: ...
1
vote
2answers
101 views

Computation with arrays of numbers

My code is m = RandomVariate[NormalDistribution[], 100]; c = 0.1; f1 = RandomVariate[NormalDistribution[], 100]; F = Sqrt[c]*m + Sqrt[1 - c]*f1; I would like to ...
-3
votes
0answers
30 views

max heap implementation as an array [closed]

assume that a max heap is implemented as an array.The core of the "percolate down" procedure swaps a node and its smaller child if the smaller child is is less than the node.Write a program function ...
3
votes
1answer
45 views

Forcing divisions to be a machine-precision floating point divisions instead of multiplication by inverse

I want to imitate machine-precision, de facto IEEE division on Mathematica. On my quick trials I find this surprisingly hard to accomplish, since Mma rewrites a / b ...
1
vote
1answer
68 views

Problem finding constants after using DSolve

I have to solve a relatively simple PDE: $$\frac{\phi_{xx}(x,y)}{A}+\frac{\phi_{yy}(x,y)}{B}=-2 \theta$$ where $A$, $B$, and $\theta$ are constants. The code that I used was ...
0
votes
0answers
43 views

NIntegrate problems [on hold]

Sorry, I am boxed in by Mathematica again, every exit being blocked and can't find any answers on the web. This usually happens once the code is lengthy so it is hard to debug and to show with the ...
-1
votes
0answers
29 views

Will the code to be improved and give a path from one room to another? [closed]

Which software did you use? MATLAB or Audrino? or others? Can the code work for others blueprint, and give a path from one room to another?
8
votes
1answer
139 views

Scrape AJAX Website with Webdriver

I hope the new Webdriver functionality can help as the normal Import and HTTPRequest don't work. The sites I have found are a ...
2
votes
2answers
89 views

Numerically stable replacement for generalised incomplete gamma function

I am looking to replace the generalised incomplete gamma function (which appears in a solution to a problem I've posted about here) with a numerically stable formula involving other functions. This is ...
2
votes
1answer
59 views

How can I tell if a matrix is ill-conditioned or Singular by using the Eigensystem function(or LUDecomposition)?

I'm using the Eigensystem function, and I'm trying figure out whether or not it is singular or ill-conditioned. I'm using the function as so: ...
7
votes
4answers
648 views

BitNot does not flip bits in the way I expected

Can anyone explain why the last result in these statements is not the bit-flipped version of arr? ...
1
vote
1answer
32 views

How to import XLSX data as integers?

I am importing simple 0s and 1s array from Excel myDep = Import[ FileNameJoin[{NotebookDirectory[], "dependencies.xlsx"}], {"Sheets", "Data"}] All good ...
0
votes
2answers
57 views

Launch a code using the button function

How can I run the code in a cell using the "button" function. I have a big code and instead of using "Shift + Enter", I want a button to do it. Here is the code: ...
0
votes
2answers
54 views

LogLogPlot with numerical errors and warnings in NIntegrate using fine integrating steps

I have the following (long) function of g1 and ωthat I wish to integrate with respect to ω <...
0
votes
0answers
85 views

Transpose problems

it must be a table but the rows where there are ^ are breaking everything ...
11
votes
2answers
728 views

Solving “Resistance between two nodes on a grid” problem in Mathematica

In the context of resistor networks and finding the (equivalent) resistance between two arbitrary nodes, I am trying to learn how to write a generic approach in Mathematica, generic as in an approach ...
2
votes
3answers
87 views

Can the indefinite integral of this trigonometric function be written in closed form?

Mathematica isn't evaluating this integral and I'm wondering if there's a bug in how I'm asking: the function I want to integrate is $$f(\theta) = \cos^2(\theta)\sqrt{A \cos^2{\theta} + B \sin^2{\...
2
votes
1answer
64 views

How to maximize just with respect two parameters out of four?

There are some posts explaining how do we maximize a function of two parameters with respect to one of those and how to plot the resulting function: Plot a function after taking the supremum with ...
2
votes
1answer
26 views

Trouble using ParametricNDSolve in Manipulate

I have troubles to understand how to use Manipulate and ParametricNDSolve to have modulable parameters inside my models. I ...
4
votes
1answer
65 views

All the group formatting available in Mathematica

I was wondering how many pre-defined group formatting style there is in Mathematica. From Format -> Style, one see that we can go from ...

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