All Questions
88,730
questions
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9
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use of ? when not meaning help
Trying desperately to understand Michael Trott's Happy Harmonic 2017! post: https://community.wolfram.com/groups/-/m/t/2858495
What does the use of ? in ?t1, ?t2 and ? = (t21 - t12)...mean?
The ...
- 1
0
votes
0
answers
8
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0-1 test or Lyapunov exponent, to prove my below system is chaotic?
The following question is a part of my research here,I want to calulate the Lyaponov exponents of the following dynamics to show whether i have a chaotic dynamics or not. $$
\ddot{x}-ax+bx^{3}+cx^{5}...
- 387
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votes
0
answers
9
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Using NDSolve on piecewise-defined system of ODEs
I'd like to use NDSolve to solve a system of n coupled 1st-order linear ODEs expressed in matrix-vector form, but which are definied piecewise in n-space (in particular, to represent different linear ...
0
votes
1
answer
22
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Determining size of the list top level
I would like to determine how many top level list elements I have. However, I need it to work like this:
...
- 3,436
0
votes
0
answers
13
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Singular Value Decomposition of a matrix over the complex plane using parallel table
I have a big matrix $M(z)$ where $z$ is a complex number. The matrix is also dense. I am trying to compute the smallest singular value of the matrix over the complex plane. Since the computation at ...
- 301
3
votes
1
answer
17
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0
votes
1
answer
25
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Solving equations involving elliptic functions
I have this:
sol = a^2 + b^2 - c^2 + 2 (c^2 - a^2)*JacobiDN[Sqrt[c^2 - a^2]*x, m] ==
u /. {m -> 1}
And I want to find its inverse, i.e. express x in terms of u. ...
- 157
0
votes
0
answers
43
views
Pdf export is heavily flawed for simplest possible notebook such as a=b+c
File > save As ... > pdf (or print as pdf) gives me extremely bad results even for the most basic simplest possible Mathematica notebooks.
Here a simple example where I can reproduce the problem....
- 111
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votes
0
answers
12
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Why is Mathematica not solving a differential eigenvalue problem with Robin boundary condition correctly?
I am trying to solve for the natural frequencies of a rod vibration problem. The BVP to be solved is
u''[x]+\[Omega]^2 u[x] == 0
subject to the boundary conditions
...
- 21
1
vote
0
answers
13
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How to use RowReduce with AugmentedMatrix [duplicate]
I have used code in this post to reach the following for a classroom example that involves a 2d abstraction framed in a 3d illustration
...
- 682
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votes
0
answers
22
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(Desmos) I'm getting the error "Too many variables", but I used only Latin letters [closed]
I don't know if I'm on the right place to ask desmos related stuff, but I'm not sure where else to ask, so here I go:
I get the error "too many variables".
I am using multiple variables as ...
- 1
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votes
0
answers
10
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Global fitting of multiple experimental datasets by solving ODEs under different conditions
I'm trying to perform global fitting analysis by solving ODEs for six different experimental datasets under different conditions.
I tried to do it using MultiNonlinearModelFit and ParametricNDSolve, ...
- 1
0
votes
0
answers
16
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Finding the inverse function when we have Jacobi functions?
I have this function
u = JacobiDN[Sqrt[b^2 - q^2]/k*k*x, m] /. {m -> 1}
And I want to find the inverse, i.e., give it in terms of x instead of u
I'm finding the ...
- 157
1
vote
3
answers
52
views
Evaluate using Mathematica or otherwise $\int_{0}^{\pi/2}\sin^n x \ T_n(\sin x)\ dx$
Denote $T_n(x)$ as Chebyshev polynomial of the first kind (see here). Then I need to evaluate for $n$ a odd natural number $$\int_{0}^{\pi/2}\sin^n x \ T_n(\sin x)\ dx $$
I am requesting a code with ...
- 97
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votes
0
answers
16
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Cut a piece of an image and obtain FFT
I have an image that is all zero except for a square in the middle of it.
Can I compute the fast Fourier transform (FFT) of that square which is smaller and less time-consuming and obtain the FFT of ...
- 1
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votes
0
answers
59
views
How to publish a Mathematica notebook to a journal as supplementary material?
I've done part of a proof via Mathematica. In the appendix of the paper I've linked to this published notebook, since I misunderstood "With any paid subscription plan, all files stored in the ...
- 111
1
vote
1
answer
27
views
Plotting Polar Solution of NDSolve
I want to plot a solution to the Geodesic equations for the Poincare disk in polar coordinates (though these may be wrong. I want to plot these as a way to check my answer):
$$\ddot{r}+\frac{2r}{1-r^2}...
- 113
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votes
0
answers
32
views
How to render text at a specific height in pixels?
I would like a way to create an image of text that is a specific height in pixels. In the following code, the text is sized to fit in the specified raster. Since there are five letters, we expect each ...
- 1,907
1
vote
1
answer
71
views
Confusion about the code
1.First, I defined the spherical harmonic function and converted it to Cartesian coordinates.
...
- 1,130
4
votes
0
answers
40
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Difference between direct plotting and using function to plot
Edit: Syed's and Lukas's suggestions both solve this problem, thank you very much.
I'm having some issues with a set of plots I'm making (it's to do with Penrose diagrams, but that's probably not of ...
- 41
4
votes
1
answer
72
views
Finding positions of sublists matching a criterion
I want to find in a list of couples the positions of the ones with consecutive items:
...
- 319
0
votes
1
answer
69
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I am trying to solve ODE using NDSolve mathematica [closed]
I will upload my code again after correcting Mista
4
votes
2
answers
80
views
How do I launch a kernel under Rosetta when I'm running the FrontEnd natively on Apple Silicon?
It's easy to launch a frontend under Rosetta, which will naturally start its kernels under Rosetta as well. For example, you can check a box in the Get Info window of Mathematica in the Finder, among ...
- 13.9k
3
votes
0
answers
72
views
What's up with BarChart?
Mathematica version 13.2.1.0
macOS version Ventura 13.2.1
I began having odd behavior with BarChart. I restarted Mathematica.
The attached image demonstrates the ...
- 14.2k
0
votes
0
answers
19
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FinancialIndicator does not work in InteractiveTradingChart with list form of stock data
I want to add some FinancialIndicator on InteractiveTradingChart when stock data is written in the form of list, ...
- 371
0
votes
0
answers
62
views
Evaluating Fourier transform in mathematica
I am trying to evaluate the expression
FourierTransform[[m (a^2 - t^2 - I g t)]^-1, t, ω]
in Mathematica. It gives me the error message that "Syntax: "[m(...
- 157
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votes
0
answers
20
views
manipulating animation
The following code defines a function P[...,X,Y,...] and plots its (random) points with coordinates (X,Y) on a plane as an animation. The number of points is determined by the variable "particles&...
0
votes
1
answer
61
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How to reproduce such Graphics3D? [duplicate]
The questioner asked how to reproduce a graphic that very closely resembled this graphic:
Shortly afterwards, my browser crashed. meta.stackexchange.com states that they do not plan on supplying a &...
- 497
0
votes
1
answer
46
views
Handling singularities like (x-y) in the denominator while evaluating double integrals
I have to solve an Integral of the following type
...
0
votes
0
answers
64
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Approximating Exp[-x] in partial fraction form [duplicate]
I'm looking to obtain order-$k$ approximation of $\exp(-z)$ for real-valued $z$.
$$R_k(z)\approx \exp(-z)$$
The constraint is that I need the result in partial fraction form, ie:
$$
\begin{equation}
...
- 6,837
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votes
0
answers
50
views
How to solve the problem with the error in FindRoot for non-linear equation?
Whoever is reading this have to be patient as the code is slightly long and I have explain each section in order to explain the problem. So I want to solve the set of non-linear algebraic equation ...
- 559
0
votes
0
answers
22
views
How to increase precision close to a irregular singular point of a numerical solution?
Using for example an ODE like
ode = t^3 y''[t] + t y'[t] + y[t]
with the following boundary conditions
...
- 13
1
vote
1
answer
31
views
Why does the image of this parameterization appear disconnected?
Why the image of this parameterization appears disconnected. Thanks.
...
- 113
-2
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0
answers
80
views
How can I solve symbolically this coupled first order ODE? [closed]
S a [ T ] ^ 3 + ( 1 / 2 ) * f Cos [ γ [ T ] ] + a [ T ] ( σ ω - ω γ ′ [ T ] ) ⩵ 0
and
...
- 1
0
votes
1
answer
45
views
Adding unit square axes to an array plot
I want to take the image created by ArrayPlot of a matrix A and add axes with the origin at the top left so that the image looks like the density plot of a function on [0,1]^2.
...
5
votes
0
answers
70
views
Using `Real32` numbers in Mathematica?
Is it possible to use Real32 format in Mathematica for matrix operations and does it make sense for performance?
For high-dimensional vectors, high precision is an ...
- 6,837
4
votes
3
answers
139
views
HoldForm not working with Map
I am debugging a ListPlot implementation and I need to see the command. To avoid huge list of numbers, i just need the ListPlot ...
- 3,436
1
vote
1
answer
51
views
Format[] and Power[]
Suppose I have a simple dot product function DP that I want to display nicely, I might use e.g.
Format[DP[x,y],StandardForm]:= (x\[CenterDot]y)
If x == y, then I'll ...
- 695
0
votes
2
answers
75
views
Setting up a PDE for a time-independent Schrödinger equation
I am trying to solve a 2d Schrödinger equation with a non-separable potential because I want to calculate the probability of reflection for different angles of incidence of a plane wave.
Here I ...
- 1
0
votes
1
answer
52
views
The code text3D facing the screen instead of rotating
As a known issue, Mathematica always keeps Text on top of everything in Graphics3D. There are some ways to avoid this, and one of them is wonderful function text3D: Placing text in 3D (not facing ...
- 225
2
votes
0
answers
29
views
How to remove the background color for the regionfunction option in contourplot3D? [closed]
Suppose that I want to plot only a part of a given surface using ContourPlot3D, such as the upper hemisphere of a sphere. I could do this using the RegionFunction option as follows:
...
- 193
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votes
1
answer
84
views
0
votes
1
answer
65
views
Finding inverse functions
Perhaps I'm not using the built in functions correctly, but I have a function f[x]. I want to find a function g[x] (its inverse) such that f[x]*g[x] = 1. This seems like something mathematica would ...
0
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0
answers
47
views
2
votes
1
answer
79
views
Stefan problem with mixed bc
I am trying to solve through Mathematica the classical Stefan problem
$$
\left\{
\begin{array}{lll}
\dot{v}(x,t)=v_{xx}(x,t) & x\in(0,s(t))\\
\dot{s}(t)=-v_x(s(t),t) & x = s(t)\\
v(0,t) = 0 &...
- 21
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votes
0
answers
56
views
How to inverse a function?
I have a function:$$D_j\left(\beta_j,B\right)=B\left(\left(\frac{1}{4}-\frac{\beta_j}{B}\right)\left( 1-\left(1- e^{-30\beta_j/B} \right)^8\right)+\frac{2/B}{3+1/B^2}\left(1- e^{-30\beta_j/B} \right)^...
- 771
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votes
2
answers
73
views
Plotting natural log equation in 3D plane
I have a natural log equation from excel and I need to plot it on 3D plane at a particular z(for example, z=1)
I would expect a vertical plane, but what I am getting is a horizontal plane.
This is ...
- 9
2
votes
2
answers
182
views
Sorting a List Based on a Given Order
Suppose I have the following input:
input={{1, 2, 3}, {-2, 4, 6}, {-1, 3, 6}}
How can I sort it according to this list:
...
- 2,293
0
votes
0
answers
23
views
Using HTTPRequest to Obtain an Access Code
I am trying to create a Mathematica equivalent to the following code:
...
- 307
0
votes
0
answers
30
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How would I convert AircraftData[] to an Entity[] that could be used with ImageIdentify[]?
I am working on a Design of Experiments to determine the image adjustment settings for a given collection of aircraft images to maximize the probabilities of correctly identifying the aircraft types ...
- 2,185