All Questions
92,214
questions
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answers
5
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Recovering formulas for sequences with integer coefficients
Suppose I know the sequence is of the $a n^4 + b n^3 + c n^2 + d n$, with positive integers $a,b,c,d$, what is the easiest way to get them from the first few coefficients?
Here are the sequences I'm ...
- 8,103
0
votes
0
answers
15
views
Destructuring the left-hand-side of `Optional[s:v]`
It is useful to be able to provide default values in pattern-matching, for example, if an element has a key but no corresponding ...
- 1,773
0
votes
0
answers
7
views
ComplexRegionPlot - Plot transform of z
Using ComplexRegionPlot, how can I please plot a transform/function of the input variable $z$?
As an example, considering $(*)$
...
- 13
0
votes
0
answers
11
views
Manual updating of function in Do loop
Previously I had asked a question about solving Maxwells equations with boundary conditions, here Machine overflow when defining boundary conditions.
I have managed to successfully run the code ...
- 21
0
votes
0
answers
20
views
Clarification of copyright in submissions to Wolfram Function Repository
the DATA repository has a statement here ...
https://datarepository.wolframcloud.com/submission-agreement
but what about FUNCTIONS?
Does 3rd party use include (say) compiling the source into another ...
- 403
0
votes
0
answers
24
views
Fitting delay differential equations (DDE)
I have the following differential equations:
$$S'(t) = 0.31 S(t) \Big( 1 - \frac{S(t)}{6.19} \Big)- \frac{a}{1 + B(t)} S(t),$$
$$B'(t) = c (1 - B(t)) - d B(t) S(t) - 3 c (1 - B(t - 18)),$$
where $B(t -...
- 41
0
votes
1
answer
22
views
How to reproduce Eugen Jahnke's drawing of a complex function
Eugen Jahnke (1863 - 1921) studied mathematics and physics at the Humboldt University of Berlin, where he became a professor at the Mining Academy in 1905.
His "Tables of Functions with Formulae ...
- 48k
0
votes
1
answer
24
views
0
votes
0
answers
27
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Why can't Mathematica simplify $\left(e^{t/m}(gm)^{1/k}\right)^{-k}$? [duplicate]
It seems Mathematica can't simplify this
Simplify[(e^(t/m)*(g*m)^(1/k))^(-k)]
The result is
I think it should be
- 445
1
vote
2
answers
60
views
How to find Maximize of $(m^2 + n^2)/(5 - m n)$ where $m$, $n$ and $(m^2 + n^2)/(5 + m n)$ are integer numbers?
I am trying to find Maximize of the expression $(m^2 + n^2)/(5 - m n)$ where $m$, $n$ and $(m^2 + n^2)/(5 - m n)$ are integer numbers. I tried
...
- 657
1
vote
0
answers
47
views
How does Mathematica compile patterns for pattern matching?
I have been trying to understand how Mathematica is able to compute the values it does. The core evaluation process is very well documented and can be found on various question over here, but they ...
- 11
1
vote
1
answer
60
views
Why is the result of "D[y == Log[x*y], x]" "0 == 1/x"? [closed]
In Mathematica 13.3.1, the D[y == Log[x*y], x] gives result 0 == 1/x. It is very weird. At WolframAlpha, its result is ...
- 445
0
votes
0
answers
11
views
Tensors without explicit specifications in xCoba
In the standard Schwarzschild setup I have the following tensor:
...
0
votes
0
answers
16
views
How to strip out Graphics exported using `FrontEnd`ExportPacket[..., "InputText"]`?
I've tried converting 913 Mathematica notebooks I've accumulated over the years into text, and the problem I ran into while using this solution is that some files are over 100MBs because they export ...
- 8,103
1
vote
2
answers
93
views
Chi-square minimization error
I'm trying to fit some data into a model using the standard procedure of minimizing the chi-square function using this code:
...
- 61
0
votes
0
answers
47
views
Method of lines - Dirichlet and mixed BC
I have a dissolution problem to solve with two equations (everything is in dimensionless form - concentration, time and distance - EDIT: that came from the second Fick's law, where the distance was ...
0
votes
0
answers
21
views
Can I delete it by specifying the number of the numbered Print Cell?
The following is a simple example.
i = 0;
Button["Make Cell", Print[Row[{CellNumbered[ ++i]}]]]
I want to give the number to the printed cell.
And I ...
- 1,470
1
vote
0
answers
18
views
Can I limit the mouse prompt position in InputField?
I wrote the Manipulate code in double quotation marks in InputField.
Manipulate[str, Style[Control@{str, " "}, 20]]
Above, I can create a prompt status ...
- 1,470
2
votes
1
answer
88
views
Extending an Animated Vector Flow from Two to Three Dimensions
I found some code for animating a two-dimensional vector flow on stackexchange. Unfortunately, I can't find the original post so I can't credit the author. I have modified the code for my purposes ...
- 5,463
0
votes
0
answers
38
views
ReplacePart will not accept coordinates [closed]
So, curiously I get an error claiming that entries like {40,80}, {41,80}... will not work as a valid positional input. I'm making these from creating a table. So, I tried manually entering these ...
- 1
2
votes
1
answer
33
views
Is there a non-allocating way to modify elements of single-reference packed arrays?
I need to repeatedly increment cuboidal chunks of a 3D image. The image is large - on the order of 1G elements.
The only way I know of doing it using built-in Image functions is:
...
5
votes
2
answers
186
views
Is it possible in Mathematica to get a step-by-step evaluation of the following?
Is it possible in Mathematica (or WolframAlpha["...]") to get a step-by-step evaluation of the following?
...
- 605
1
vote
1
answer
89
views
Unable to improve accuracy of MethodOfLines
I'm studying a PDE which roughly models a rope subjected to driving on one end. The coordinate $v$ is related to physical time $t$ via the relation $v=t-x$. I'd like to solve the initial value problem ...
- 45
4
votes
2
answers
171
views
Nonlinear model fit not working
Probably a very simple fix, but I'm trying to fit a simple exponential. Even when I put in good guesses, the model won't fit the data. Any suggestions?
...
- 75
0
votes
0
answers
63
views
Badly conditioned matrix for boundary ODE
I have a coupled boundary ODE with dependent variables $u=u(x)$ and $z=z(x)$,
$$u'' - \frac{1}{z} \left( -3 + u'^2 (3 - c\; e^{-g u} z^4) - 6 u' z' \right) = 0\tag{1}$$
$$z'' + c\; e^{-g u} z^3 (-3 + ...
- 661
1
vote
1
answer
82
views
Converting Wolfram Language Scripts (.wls) into PDFs
I have just discovered the free (as in free beer) Wolfram Engine, coming with a generous licence. After playing with Mathematica for a while, and missing the notebook feature, I would like to generate ...
- 111
0
votes
1
answer
60
views
How to plot points on a grid given by two vectors? [closed]
I am trying to do a very simple task that is automatic on Matlab for example, but it is not trivial for me in Mathematica:
Given two vectors for example:
...
0
votes
0
answers
28
views
Connection of MariaDB 11.2 to work with Mathematica 13.3.1
I would like to get the proper driver settings in place to permit the
mariaDB database to connect to Mathematica via a JDBC driver running on
a Windows11 64-bit machine.
I've got mariaDB version 11.2 ...
- 1,774
0
votes
0
answers
74
views
How is my code going over the recursion limit?
I don't know how my code is exceeding the recursion limit of 1024.
...
1
vote
1
answer
60
views
More intuitve way to simplify a simple expression involving two exponential factors
Is there a way to ask Mathematica to simplify expressions it generates, like:
$e^{-\frac{A t}{v^3}-\frac{v^2}{2 w^2}} \left(-1+e^{\frac{A t}{v^3}}\right)$
into a more readable form by taking out the ...
- 317
5
votes
1
answer
111
views
How to solve the equation $(3^m - 3^n)^2 = 2^a + 2^b$ where $m, n, a, b$ be positive integers?
I am trying to solve the equation $(3^m - 3^n)^2 = 2^a + 2^b$ where $m, n, a, b$ be positive integers. I tried
...
- 657
2
votes
0
answers
28
views
Listing most recently modified sections in Notebook?
I'd like to get a clickable list of all "Sections" that have been recently modified in my notebook, grouped by day of modification. "Modified" Section means, some cell under that ...
- 8,103
2
votes
1
answer
226
views
Absolute value of a complex number
I want to calculate |xx|^2.
Why can't Mathematica just calculate it?
What am I supposed to do here?
I just want it to actually calculate it, so that there are no imaginary numbers left.
Is that so ...
- 23
0
votes
1
answer
34
views
Searching directory over a network
I have a network drive mapped on my Windows machine. I need to read data from the network that is nested in a few directories below the root. Example is "G:/Data/folder01/data/date_name/values....
- 11
2
votes
1
answer
38
views
By what criteria does Mathematica generate the list of group elements in `GroupElements[group]`?
I ask because aside from always giving the identity element first, I have found a "pattern" associated with the list given by GroupElements[group]. This &...
- 303
0
votes
0
answers
62
views
Solving the integral equation
Why does Wolfram Mathematica just rewrite my code instead of solving the integral equation? SigmaPhiBegin, SigmaPhiEnd are functions depending on Rho, Rho, bEnd, a, Kappa are constants. What needs to ...
- 1
2
votes
1
answer
45
views
Export Notebook as Text (in 13.3 &14)
What is the best way to export a notebook as readable plaintext - while preserving as much structure as possible? The motivation here is the need to bulk-ingest notebooks and chunk them (for use in ...
- 3,601
-1
votes
0
answers
27
views
Specify a tensor or a function with a specific form in xCoba [closed]
Suppose, in the Schwarzschild geometry with the standard coordinates, I wanted to specify an electromagnetic tensor F with the (six) components all being functions of r: A(r), B(r), C(r), D(r), G(r), ...
1
vote
3
answers
104
views
Plotting |z-2| < 1 under w = z/(z-1)
How can I plot the image of |z-2| < 1 under the transformation w = z/(z-1)? The expected result should look something like ...
- 507
1
vote
1
answer
90
views
Mathieu Floquet solution
Mathematica provides the MathieuC[a,q,z] and MathieuS[a,q,z] functions - as well as some other Mathieu-related functions. Maple ...
- 11
7
votes
1
answer
146
views
Can you explain this substitution rule?
This rule behaves as I expect:
b . c + a . b . c /. (b . c) -> x
(* x + a . x *)
I would expect the same result with this:
...
- 16.2k
8
votes
5
answers
1k
views
Why does Mathematica not recognize a convergent series?
In one of my program run on Wolfram Cloud I run the command:
Sum[(-1)^(Floor[k/2])/(k+1),{k,0,Infinity}]
and got the response
...
- 689
0
votes
1
answer
33
views
What is the fastest way to change Python environment?
We can see all registered Python environments through FindExternalEvaluators["Python"].
But the user interface will use the last registered one.
How to ...
- 9,486
3
votes
1
answer
39
views
Alternatives to Export to write long list as a table on a file
I have a large list (approx 50 millions elements).
I could Export it as a table like this:
...
- 6,587
0
votes
0
answers
98
views
Plot and mention extremum with corresponding points of extrema
Let sigma1[v] , sigma2[v] and sigma3[v] with Im(sigmar)<0 (r=1,2,3) are the roots of the following cubic (in sigma^2) Eq (1), say:
...
- 31
1
vote
0
answers
36
views
How to place Objects in Graphics in front or behind other objects using Inset[] in Mathematica13.3?
I made several 2DGraphics using Mathematica v12.0.
To define if an object is placed in front of another or behind, I simply changed the order of the Inset. In this ...
- 103
1
vote
0
answers
36
views
How to assume a function is holomorphic?
For example, for a holomorphic function $f(z)=f(x,y)$, it's well know that $\ln |f|$ is harmonic. I want to check it with mathematica with the following code:
...
- 11
15
votes
1
answer
610
views
How can we plot Man Ray's "Shakespearean Equation" w == e^(1/z)?
1. Man Ray
Man Ray (1890 - 1976) was an American artist who spent most of his career in Paris. He was a significant contributor to the Dada and Surrealist movements. Man Ray produced major works in a ...
- 48k
0
votes
0
answers
28
views
Create Constraints Iteratively for NMaximize [closed]
new to Mathematica so sorry for the silly question
Trying to crete a list of constraints in Mathematica without typing manually as
...
0
votes
0
answers
35
views
The Value is not Updated in the list/table [closed]
I have following data
groupedTerms3rdcycle = GroupBy[term3rdcyclelist, Most -> Last];
where term3rdcyclelist is the list.
I ...
- 123