Unanswered Questions
646 questions with no upvoted or accepted answers
10
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Modelling Hysteresis with a Differential Equation
I want to implement the bulk ferromagnetic hysteresis model (mostly the Jiles-Atherton Model), see http://drum.lib.umd.edu/bitstream/1903/6043/1/PhD_99-1.pdf page 44 equation (30).
The needed ...
- 117k
9
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0
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977
views
Solving the 2D Schrödinger equation with eigensystem, then verifying orthonormality of eigenfunctions with NIntegrate
I am solving the time-independent 2D Schrödinger equation for an interacting electron and hole in the case of anisotropic electron and hole masses, where the interaction is described a modified form ...
- 42.2k
9
votes
0
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562
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Spurious Error Messages from NDSolve when Using WhenEvent with Time Delays
Bug introduced between versions 10.1 and 10.4, and resolved in 11.3.
Using either 11.2 or 10.4 on Windows 10 (64 bit), I am unable to reproduce the answer by March to question 99576. Specifically,
...
- 63.1k
8
votes
0
answers
197
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Bug in integral related to beta distribution
I've encountered a problem, which I'm pretty sure is a bug. I've contacted Wolfram's support and they were less than helpful. I'd like to bring the issue up here to get either a confirmation that it ...
- 311
7
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0
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436
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Integrating rational functions of several variables over $\mathbb{H}^4$
Let $W$ be a rational function of $8$ variables $a,b,c,d,e,f,g,h$ from this file, e.g.:
...
CommunityBot
- 1
6
votes
0
answers
186
views
ParametricNDSolveValue causes kernel to crash
Bug introduced in 12.1.1 and persisting through 13.2.0.
In the course of answering question 228693, I found that
...
- 42.2k
6
votes
0
answers
7k
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What's the most difficult multidimensional integral that Mathematica has solved?
I am interested in benchmarking numerical integration methods and am trying to develop a wider set of difficult multivariate examples. For my particular methods, I only want to look at non-negative-...
- 3,167
6
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0
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211
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Details of NDSolve calling LSODA
Inspired by my question regarding the computation time of NDSolve using the LSODA backend I was wondering how NDSolve is actually calling LSODA (what arguments are sent to LSODA), i.e. what are the ...
6
votes
0
answers
511
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What are good/best practices to take the Fourier transform of an InterpolatingFunction?
I have a function which I have obtained from numerical integration of a differential equation, and I would like to take its Fourier transform. What are good practices for doing this?
To make things ...
CommunityBot
- 1
6
votes
0
answers
187
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Modify NDSolve`StateData (if possible)
I am trying to solve a PDE that needs to be scaled constantly (refer to this). @andre suggests I modify NDSolve`StateData.
Now, the problem is, I'm not used to ...
CommunityBot
- 1
5
votes
0
answers
147
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"Glueing" interpolating functions
Suppose we have two interpolating functions with exactly touching domains, in our case {-1, 1} and {1, 2}.
How to "glue&...
- 32.8k
5
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0
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249
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Hypergeometric Function Integration Using Mellin-Barnes Representation
I have the following integral:
$$
I=\int_0^1 d \alpha d \beta d \gamma r(\gamma) s(\alpha, \beta) T(\alpha, \beta, \gamma)
$$
where I define
$$r(\gamma)=(\gamma(1-\gamma))^{ -1 / 2+\epsilon / 2}$$
and,...
- 139
5
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0
answers
224
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Are there any dedicated built-in methods to NIntegrate over the unit sphere or the 3D rotational group?
As part of a molecular-physics calculation, I need to perform an integral to find the average of a certain function over all the possible orientations of the molecule,
$$
\langle f(\mathbf v)\rangle = ...
- 10.5k
5
votes
0
answers
182
views
Numerical verification of the estimate:
How to verify numerically with considerable accuracy in Mathematica the following :
$$\int_2^x\dfrac{1}{z\Gamma(\sin^2[π\Gamma(z)/(2z)])}dz\sim\ln(\ln(x))$$
?
I need more suitable and better code ...
- 223
5
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0
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276
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StiffSystem or Singularity - a system of second order ODEs in the problem of geodesics
I would be extremely grateful for any help regarding the following code I wrote and the errors it produces. In this code I am investigating the behaviour of a massive particle trapped in the vicinity ...
- 151