All Questions
88,730
questions
0
votes
0
answers
9
views
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 ...
0
votes
0
answers
8
views
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}...
0
votes
0
answers
9
views
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
views
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:
...
0
votes
0
answers
13
views
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 ...
3
votes
1
answer
17
views
Convert list of conditional expressions to list
I have a long list of items of the form
...
0
votes
1
answer
25
views
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. ...
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....
0
votes
0
answers
12
views
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
...
1
vote
0
answers
13
views
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
...
0
votes
0
answers
22
views
(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 ...
0
votes
0
answers
10
views
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, ...
0
votes
0
answers
16
views
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 ...
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 ...
0
votes
0
answers
16
views
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 ...
0
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 ...
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}...
0
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
vote
1
answer
71
views
Confusion about the code
1.First, I defined the spherical harmonic function and converted it to Cartesian coordinates.
...
4
votes
0
answers
40
views
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 ...
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:
...
0
votes
1
answer
69
views
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 ...
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 ...
0
votes
0
answers
19
views
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, ...
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(...
0
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
views
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 &...
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
views
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}
...
0
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 ...
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
...
1
vote
1
answer
31
views
Why does the image of this parameterization appear disconnected?
Why the image of this parameterization appears disconnected. Thanks.
...
-2
votes
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
...
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 ...
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 ...
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 ...
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 ...
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 ...
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:
...
0
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
votes
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
$$
\left\{
\begin{array}{lll}
\dot{v}(x,t)=v_{xx}(x,t) & x\in(0,s(t))\\
\dot{s}(t)=-v_x(s(t),t) & x = s(t)\\
v(0,t) = 0 &...
0
votes
0
answers
56
views
How to inverse a function?
I have a function:$$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)^...
0
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 ...
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:
...
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:
...
0
votes
0
answers
30
views
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 ...