All Questions

1
vote
1answer
63 views

Finding the limiting cases for the root of a function

I'm sorry my title is not descriptive; the function I am interested in is too long to put in there. What I am studying is the real, positive roots of the following function: $f(\epsilon) = (\Delta^2-\...
0
votes
2answers
59 views

Matrix square root and commutation

Does a square of a matrix commute with the matrix itself? I have the following code showing that it does not. Is everything fine here? ...
2
votes
1answer
57 views

Access to the temporary solution in NDSolve with StepMonitor

I want to step-monitor at each time step of a spatio-temporal NDSolve (using the finite element method) the maximum bending of the function sampled over the curent mesh. For this I first need access ...
0
votes
1answer
24 views

Changing the integration equation in NDSolve upon an event

I'm trying to implement the solution to the following ODE dx/dt = -x for x < 0 dx/dt = x for x > 0 Using NDSolve and ...
0
votes
0answers
90 views

Why can't Nsolve find the solutions for my equations?

I have a problem using NSolve in my Mathematica code. In my Code NSolve should find a value for qw, but it won't. The strange ...
5
votes
2answers
316 views

Branching points detection in processed image

I want to get the branching coordinates from a computer-generated image like this one: After SkeletonTransform and Pruning, I ...
0
votes
1answer
43 views

NDSolveValue gives an error that a list of equations is expected

I have this system of PDE that I want to solve. I reduced my original system of PDEs to the system below to capture the error (the actual code is after the image at the buttom): Function ...
2
votes
1answer
40 views

How do I draw an angular vector field containing a domain wall?

Intuitively, an angular vector field $\theta(x)$ such as the following would describe a domain wall between two vortices/strings of opposite winding number. I would like to draw this on a computer ...
2
votes
2answers
86 views

Carnot cycle diagram

Note: I have adopted and modified code taken from Wolfram demonstration page. I want to achieve something similar to the following figure: I use the following code: ...
0
votes
1answer
39 views

Complex Infinity of Hypergeometric+Gamma function

I am solving some integral which gives an hypergeometric function+gamma function . The point is that my values of n (see the code below) are integers, so ...
0
votes
0answers
53 views

Homogeneity of a function within a region

I have 2 functions; funtion 1: ...
1
vote
0answers
32 views

Adding of Mathematica “Play” structures in Mathematica 10

I try to do some sound manipulation in Mathematica 10, because i can't upgrade to Mathematica 11 with my students license, which i realise would have a lot more to offer for Audio Processing. However ...
1
vote
1answer
35 views

Question about replacement and plot

I want to plug a value into the following solution which I defined. ...
0
votes
1answer
68 views

Help with Mathematica Plot

I'm attempting to recreate a Penrose Diagram in Mathematica from this paper: https://pdfs.semanticscholar.org/6bee/5e712cb09fdc97d38a361c9bff3e4beb0125.pdf Pg: 12,13. I'm not very familiar with ...
-1
votes
0answers
30 views
3
votes
2answers
97 views

Print integer number fraction as string of numerator and denominator

I want to convert an integer number fraction as text with a certain font, size and color: Example: ...
2
votes
1answer
43 views

Print number without preceding 0

I would like to print the number 0.21534715 as .21 NumberForm[0.21534715, {1, 2}] gives me only ...
3
votes
2answers
82 views

“Graphics is not a Graphics primitive or directive.”?

I looked through the forum but none of what I've found is helping. ...
2
votes
0answers
26 views

Geographics Geolabels and Polygons

Using Vers. 11.3.0, I've prepared Maps of the various Japanese Prefectures (ken). Here, I create 3 such maps, as follows: ...
0
votes
0answers
48 views

how to show all the points of the graph? [on hold]

how to show all the points of the graph ? I need all the corresponding {x,y} value. ...
0
votes
1answer
46 views

Simplifying expressions with square roots of squares

I have a large number of expressions that are of the form, f(a,b)+Sqrt[g(a,b)^2] I understand I can use simplify and make an assumption to get either of the two ...
0
votes
1answer
42 views

Creating matrices using a Do-loop

Here is an image of current assignment; I am not able to do step 6 to 8 When I try to do the Do-loop, it states that the {i, j} does not have appropriate bounds. ...
1
vote
0answers
24 views

Translate key events to nothing?

My Macbook Pro has a touch bar which is causing me to make a bunch of hard-to-find errors If my finger mistakenly hits the F3 through F12 positions on the touch bar, the front end inserts an ...
0
votes
0answers
26 views

Preventing single letter italics within a string [duplicate]

I want to be able to use super/sub scripts without the main character being forced in to Mathematica's math italics mode. The motivation being to preserve the font style settings on the string in ...
4
votes
7answers
278 views

Computing only Prime Powers with NestList

Is there a simple way to compute only prime powers of a function f with NestList? That is, I want to compute: {f[x_0], f^2[x_0]=f[f[x_0]], f^3[x_0], f^5[x_0]...} ...
2
votes
1answer
42 views

Converting an expression with strings to an association

I have an expression which contains a bunch of strings and some complex valued numeric factors in front. A couple of summands might look like this: ...
1
vote
3answers
48 views

How to apply a continious substitution reduction of (-1 + 3 phi - 2 phi^3 - 6 phi^4 - 20 phi^6 + 6 phi^7 + 3 phi^8 + phi^9)//.{phi^3->1-phi^2}

I have the answer to $(-1 + 3 phi - 2 phi^3 - 6 phi^4 - 20 phi^6 + 6 phi^7 + 3 phi^8 + phi^9)/.{phi^3->1-phi^2}$, that is not the problem. I am looking for a method that continues to apply this ...
0
votes
1answer
54 views

Getting an exact real solution of a transcendental equation [on hold]

I want to get the solution of E^(2x) - E^x == 6 I tried FindRoot[E^(2x) - E^x == 6, {x, 1}] which gave me the numerical ...
1
vote
1answer
26 views

Why are these arrows not plotting?

I'm very new to mathematica, so pardon me for such a simple question. I have tried to follow the syntax of the "Arrow" documentation(https://reference.wolfram.com/language/ref/Arrow.html), but I ...
0
votes
0answers
58 views

Numerical solution for the following two Korteweg-de Vries equations

I have been trying to solve the following Korteweg-de Vries (KdV) equations using NDSolve, but nothing went right! $\qquad 6 U_{t} + (9/2) U_{xxx}+ 9 U U_{x} - 6 a ...
1
vote
1answer
56 views

Exporting Data to NetCDF

I previously asked for help with accessing metadata in .HDR (version 4) files. I am obliged to work also with NetCDF files, with which I am only briefly acquainted. (I am aware that my question ...
2
votes
1answer
107 views

Calculating the sum of the lengths and plotting all curves on the same map

I have a curve like below; ParametricPlot[ FromPolarCoordinates[{Exp[(t + 0)*0.5], t}] // Evaluate, {t, 0, Pi - 0}, PlotRange -> All] This curve rotates ...
1
vote
2answers
65 views

How can I extract blocks of 8 bits data from a plain text file?

I have a plain textfile consisting of 4M numbers (0 and 1's) from the number Pi. I would like to split this textfile into blocks of 8 bits (ie 8 characters). I know this can be done with StringTake ...
-4
votes
0answers
30 views

What does orthogonall mean? [on hold]

Say I have a node in a grid that effects all other nodes "orthogonally". If a node has a value of "4", than it increases the value stored in the other orthogonal nodes next to it by "1". So If the ...
4
votes
1answer
105 views

Setting Some Elements in a Matrix to zero

Assuming I have the a 5x7 matrix below: b = ((1, 4, 9, 16, 25, 4, 2), (36, 49, 64, 81, 100, 5, 1), (121, 144, 169, 196, 225, 8, 9), (256, 289, 324, 361, 400, 9, 5), (441, 484, 529, 576, 625, ...
1
vote
1answer
53 views

Nested Do loops with externally defined iterators

I want to be able to define a set of iterators for nested Do loops, such as ...
1
vote
3answers
64 views

3D Plot the result of local Minimize with varying parameter values

I'm faced with the following minimization problem: Find $r\in[0,1]$ that minimizes $\frac{d^2+k^2 (1-2r)r}{2(1-r)r}$, which is bounded by 0 and 1. In addition, $k<d$ holds and each of $d$ and $k$ ...
9
votes
1answer
105 views

Option Lighting in the Show function does not work

Bug introduced in 11.2 or earlier and persisting through 11.3 There are something wrong when I try to evaluate the example from Lighting Docs, here is the code: <...
2
votes
3answers
139 views

Force a sum to be simplified

I want to force this sum to be simplified to 1 Sum[Cos[(Pi*l*(2*m + 1))/(n + 1)], {l, 0, n}] Only DiscretePlot3D gives the correct result showing all point to 1
0
votes
0answers
37 views

Variable Plotted in 3d Space

I am trying to plot dose rate in 3d space in terms of r, theta and z. None of the variables are functions of each other they are just arrays of points with the following sizes: Dose 220x35 r 220x35 z ...
0
votes
1answer
34 views

Changing variables to obtain derivatives of new variables [duplicate]

Let's say that I have some symbolic expression of a function $x(t)$, and would like to obtain its derivative $x'(t)$. However, I also have the following two identities, $\xi = \omega t$, and $\eta = ...
4
votes
2answers
112 views

Simulating ndgrid function of MATLAB

I know that there has been an answer on meshgrid function of MATLAB. For functions involving more than 3 variables, this function does not work. In MATLAB, the ...
5
votes
1answer
71 views

Automatically rotate frame ticks labels

Say in ListPlot[Range[0, 1, 0.1], Frame -> True] I want the tick marks on the vertical axis to be rotated 90 degrees. How to do it automatically, preserving ...
0
votes
1answer
63 views

How to get function of “GaussianProcess” prediction?

I am a new user of Wolfram Mathematica. I need your help. Let's say I have three variables: x, y, z. I want to calculate the "z" depending on x, and y. In other words, I want to find a function for z ...
2
votes
1answer
65 views

Importing Data multiple times from the same File

I have a large data file (.txt) with bivariate data in the following form x1,y1 x2,y2 x3,y3 . . . xn,yn ---------F 0 x1, y1 x2, y2 . . . xn, yn --------F 1 . . . ...
2
votes
2answers
58 views

Elements Replacement

Please I need help on how to replace elements in a matrix with another elements. For example, I have a (5,5) matrix, and I like to replace elements from All rows and column 3 to 5, with zero. such ...
4
votes
3answers
218 views

How to create “Volumemesh” from closed “surfacemesh”?

Given a surface region (MesgRegion netz2D), for example ...
1
vote
0answers
32 views

Shortcuts in Wolfram Cloud

When I use the cloud version of mathematica, the shortcuts like "cntrl /" and https://reference.wolfram.com/language/guide/NotebookShortcuts.html don't work. I believe it is because the browser ...
0
votes
1answer
68 views

(Updated) How do I fix a Discretization error?

I am attempting to model a cross section problem from Calculus II using the general slicing method. Below is the working code to generate the "slices" of the defined problem; however, I would like to ...

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