Unanswered Questions
309 questions with no upvoted or accepted answers
49
votes
0
answers
3k
views
Fast Spherical Harmonics radiative transfer
This is a rather specific question and I apologize for spamming you with some lengthy code. But it could be interesting for some reader and maybe you can help out, so please bear with me.
I am using ...
- 141
12
votes
0
answers
289
views
Weird behavior of the AbsArg function
Bug introduced in 13.3 or earlier and fixed in 14.3.
I have encountered a very strange behavior of the listable AbsArg function on
...
- 41.5k
11
votes
0
answers
238
views
How to modify NDSolve`StateData without crashing the kernel?
Probably a hard question, but it's better to cry out loud.
Reminded by Chris K, I noticed my fix function has been broken since v11.3. After some checking, I ...
- 71.6k
8
votes
0
answers
197
views
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
8
votes
0
answers
511
views
Mathematica 7: "LessEqual::nord:" error when using NMinimize on a real function
Bug introduced in 7.0 or earlier and fixed in 9.0
I encounter a problem (Mathematica 7) similar to Strategies to avoid LessEqual::nord in NMinimize? but the advised strategies don't work for me. Also, ...
CommunityBot
- 1
7
votes
0
answers
3k
views
Does NSolve find all solutions?
Is the solution set returned by NSolve usually complete? Can I assume that there are no more solutions than what it returns? Consider systems of equations e.g. ...
CommunityBot
- 1
6
votes
0
answers
101
views
What makes ListPlot better than N?
I wanted to numerically verify the validity of the formula for the first Stieltjes constant
$$\gamma_1=-\frac12\sum_{n=0}^\infty\frac1{n+1}\sum_{k=0}^n\binom{n}{k}(-1)^k\log^2(k+1)$$
...
- 10.1k
6
votes
0
answers
211
views
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
2k
views
Numerically solving system of partial differential equation
I am trying to solve a system of partial differential equation with boundary conditions. But I got an error message saying
NDSolve::icfail: Unable to find initial ...
- 567
5
votes
0
answers
147
views
"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
votes
0
answers
367
views
Change Branch Cut for DifferentialRoot
The differential equation
eqn = (16 + q) g[q] + 4 q (-3 + q^2) g'[q] - 4 q^2 (-1 + q^2) g''[q] == 0
is singular at {-1,0,1}. ...
- 63.1k
5
votes
0
answers
182
views
Speed up computing the $n$-th hexadecimal digits of $\pi$, by using BBP formula
Let
$$S_j=\sum_{k=0}^{\infty} \frac{1}{16^k(8k+j)}$$
Then
$(n+1)$-th hexadecimal digit of $\pi$ given by the fractional part of
$${\lbrace 4\lbrace 16^{n} S_1\rbrace-2\lbrace 16^{n} S_4\rbrace-\...
- 9,126
5
votes
0
answers
111
views
How to pass a custom method to a particular option?
In an answer to my question More efficient method to compute moments of the Johnson $S_B$ distribution, J. M. has come up with a method to compute the moments of the Johnson $S_B$ distribution, which ...
CommunityBot
- 1
5
votes
0
answers
148
views
How to speed up solution of system of recurrence equations
I was wondering how I can improve the speed on this method for solving a particular system of coupled recurrence equations. The system is
$$
\begin{align*}
&V(m)=\alpha + \beta V(m+1)+\beta \sum_{...
- 114k
5
votes
0
answers
380
views
NMinimize seems to call function with the same values multiple times
I have to minimize a function where the evaluation of one parameter set takes very long (around 5sec) and discovered alongside, that NMinimize seems to call this ...
- 1,053