All Questions
93,664
questions
0
votes
0
answers
11
views
Instantaneous Growth Equation
Find a formula for y[x] if it is known that the instantaneous growth rate y'[x] is proportional to y[x] and it is known that y[0]=5 and y[5.7]=10.
Does the value of y[x] double every 5.7 years?
I ...
0
votes
1
answer
53
views
Can Mathematica return the closed forms of 'arbitrary' function compositions?
I have only just downloaded Mathematica, so I am entirely new to this software.
Here is what I am trying to do:
If $f(x) = \frac{x}{2}$ is an example function, and $f^{(n)}(x)$ is the composition of $...
2
votes
2
answers
40
views
Reverse association and map through its values/keys
I suspect this could be done in a shorter and more readable code:
Challenge: do it without Normal and Association.
...
1
vote
0
answers
38
views
Problem with using RuleDelayed (:>)
I have defined a rule using rule delayed function as follows:
innerWithDxU = (f1_ D[f2_[x,y],x]f3_[x,y] :>-f2 [x,y]D[f1 f3[x,y],x] );
...
4
votes
2
answers
58
views
How can I find values of m so that the function $\frac{-m+x^2+x-4}{4 x-m}$ increasing in the interval $(1,2)$?
I am trying to find value of marameters $m$ so that the function $f(x) = \dfrac{-m+x^2+x-4}{4 x-m}$ increasing in the interval $(1,2)$?
I tried
...
3
votes
4
answers
54
views
How to make expression-dependent replacements?
Consider as a toy example that I want a replacement
which acts on
{x,1,2,3}
by replacing $x$ with the length of the list itself. In this example this should output
...
3
votes
2
answers
58
views
FindRoot changes results from ParametricNDSolve
I solve numerically an equation, and I get the expected behaviour like the following graph
But if I use FindRoot to get the roots before plotting, the plot of my ...
3
votes
1
answer
90
views
How to avoid circular refs in Language`ExpressionStore
Expressions are not garbage collected if there are references to them stored in the expression store. I use the following internal functions:
...
-1
votes
0
answers
58
views
Strange plots by Mathematica [closed]
I think the picture speak for itself. Why is the x axis at y=1?
Thanks
4
votes
1
answer
110
views
3D FEM Memory Problem with Hexahedral Elements & V14 & Apple Silicon
After using MM V12 for a long time on a MacBook Pro 2011, which just lost 8GB or RAM from 16GB, I am trying V14 on a MacMini M2pro with 32GB. I had previously coded a coupled 3D EM problem involving a ...
0
votes
2
answers
59
views
Generating lists where new elements depend on the previous element
I am interested in using some type of list or table in-built Mathematica function to generate a list, where the elements of the new list not only depends on the input values of a previously defined ...
3
votes
2
answers
95
views
Calculating vertical displacement to intercept the perimeter of the circle after a horizontal shift
I can't come upon a solution for the question below. The background of the actual work is not interesting for the question, so l won't explain why I need the solution. I would be very thankful if ...
2
votes
0
answers
103
views
Is there a way to force 'Simplify' to use some assumptions?
First time poster. I have a basic question about 'Simplify'.
I am encountering a problem when trying to simplify some algebraic expressions, where I find an unexpected behaviour of the 'Simplify' ...
6
votes
5
answers
162
views
How to create sublists of a list based on the relation between their elements?
I have a large data set looking like this:
...
6
votes
5
answers
253
views
How to remove extra brackets from a list?
I have a list which looks like the following:
list1={{{a,b,c},{a1,b1,c1},{an, bn,cn}},{{f,j,k},{f1,j1,k1},{fn, jn,kn}}}
And I need it to be as follows:
...
2
votes
2
answers
50
views
DiscretizeRegion fails on a simple implicit region
No matter what option I set to DiscretizeRegion it fails on the region (missing second line).
What else can be done?
...
0
votes
0
answers
38
views
Assign the result to the lists [duplicate]
I am following the solution of the mixing eigenvalues from Carl Woll's answer in this post. In the end, the eigenvalues are plotted using this formula
...
3
votes
2
answers
132
views
How to draw a curve projection?
I want to draw the following projection picture for the cuspidal cubic curve in Mathematica. Does anybody know how to do this?
2
votes
3
answers
469
views
Why is Mathematica not simplifying eigenvalues?
For matrix A = {{x*Exp[I*y], z}, {z, x*Exp[(-I)*y]}}; , Mathematica yields the following eigenvalues:
...
3
votes
3
answers
163
views
Find maximum and minimum
I have been trying to find the max and minimum values and make it to a list. I have been using some of the previous forms and it doesn´t work.This is my function:
...
2
votes
2
answers
102
views
Conic sections: intersection of a plane and a cone. How can I change the equation of the plane to get conic sections automatically?
I tried to draw intersection of a plane and a cone.
Hyperbola
...
5
votes
4
answers
329
views
Still on Filling
I am really sorry to bother you for the same problems, but I cannot get in the view about this command, the filling option.
What I want: to fill the semicircle part, under the $y = x$ curve.
Here is ...
2
votes
0
answers
69
views
How to use GPT-4 vision?
How exactly do you call GPT vision, both programmatically and in chat-enabled notebooks?
It seems like the image is being downsized when pasted inline, and it is unclear how many prior cells are in ...
0
votes
0
answers
39
views
How to quickly sample points according to the given distribution?
Consider the following points sampler:
...
0
votes
1
answer
87
views
Numerical Fourier transform
I am having issues trying to numerically Fourier transform the following function
\begin{equation}
f(x) =\frac{1}{x^6}\sqrt{4m^2x^2+x^4}\log\biggm(\frac{2m^2 + x^2 + \sqrt{4m^2x^2+x^4}}{2m^2}\biggm)
\...
0
votes
1
answer
138
views
How to solve this geometric problem with Mathematica?
I try to solve the following problem, making use of 14.0 on Windows 10
Let a triangle $\Delta$ (a contour with its interior) be chosen in the unit square $S$.
To prove that the closure of the ...
9
votes
5
answers
332
views
Reconstruct list from its PositionIndex
Is there a more elegant or shorter way of reconstructing a list from its PositionIndex?
The following I regard quite cumbersome:
...
2
votes
2
answers
104
views
How to get angles along a line?
What is the best way to get the angles along a line?
I have tried this for example:
...
0
votes
1
answer
54
views
Understanding the example of sensitivity analysis in Documentation using ParametricNDSolve
There is an example in Documentation for studying sensitivity analysis, using ParametricNDSolve:
...
0
votes
0
answers
39
views
Why does NSolve does not give solution what Solve does [closed]
I have 47 set of linear system of equations. The Solve command is giving the answer, but NSolve is unable to return answers. The parameter values are same in both cases.
If I calculate the values ...
4
votes
1
answer
184
views
Fourier Transform of 2D data using Fourier
I don't understand the documentation of Fourier. My goal is the get the coefficients of the Fourier-series (i.e. $\sum_{n\in \mathbb{Z}} c_{n,m} e^{inx+imy}$) of ...
6
votes
1
answer
167
views
How to get properties from a Polygon object?
We can get polygons by this code:
polys = (SeedRandom[#]; Polygon[RandomInteger[20, {4, 2}]]) & /@ Range[6]
How to get those properties? When I dig ...
0
votes
0
answers
39
views
Dimensionality problem with initial conditions [closed]
I am trying to solve these two systems of equations with NDSolve, however I am getting a problem I do not know how to fix. The code is as follows:
...
0
votes
1
answer
85
views
Solving a 3+1D Wave Equation
I am having some problems with finding the solution to the magnetic field, B[x,y,z,t]. Is there anything I can change to my code to obtain a solution of B[x,y,z,t] with the initial conditions and ...
1
vote
0
answers
43
views
How to get a single line title in a Manipulate box? [closed]
I'm having a text output issue with the following code:
...
1
vote
0
answers
49
views
Why I can't install this package [closed]
I am trying to run C++ in Mathematica. I got a package "LTemplate" from the answer from Szabolcs in this post: How to simplify writing LibraryLink code?. However I can't install it.
This is ...
3
votes
4
answers
162
views
Sort Column as a Row
I have
a = {1, 2, 3, 10};
b= {2, 3, 4, 8};
t= Do[If[a[[i]]+b[[i]]>3,Print[a[[i]]],"No"],{i,1,4}];
2
3
10
I need to get the result; t={2,3,10}
3
votes
2
answers
200
views
Plotting a special 2d set in Mathematica
I have a set $S$ in $\mathbb{R}^{2}$ with the following description:
$$
S=\{x\in\mathbb{R}^{2}\mid0\leq x^{\top}y\leq1,\;\forall y\in S\}.
$$
In other words, if $x$ and $y$ are points in $S$, then we ...
1
vote
1
answer
65
views
How combine two DensityPlot3D in only one graph
I need to combine two DensityPlot3D in only one graph but the "Show" doesn't work for that.
...
0
votes
1
answer
51
views
HypExp package throwing errors when loading
I am trying to load the package HypExp by using the instructions given on the site. The package throws an error
...
6
votes
1
answer
213
views
+500
Visualizing diagrams needed to compute $\operatorname{Tr}(A^3 (A^T)^3)$
I'm looking for help getting Mathematica code to construct diagrammatic expressions like the following, obtained by River Li as a way to compute $\operatorname{Tr}(A^2 (A^T)^2)$ for $d\times d$ matrix ...
3
votes
0
answers
31
views
Mathematica call CompiledFunction from Python with Listable and Parrallelization attributes
I have a CompiledFunction e.g. this:
...
2
votes
0
answers
34
views
Take symbolic derivative of summation expression and display as unexpanded sum
My main problem here is two-fold:
Take symbolic derivative of summation expression
Stop summations from being "unrolled"/expanded, e.g., displayed as the sum of terms
I also have some ...
0
votes
1
answer
57
views
Clear Guidelines for Symbolic Calculation With Units?
The following notebook performs a relatively simple physical calculation interacting position, velocity and acceleration of two charged point particles according to Weber electrodynamics.It is simple ...
4
votes
1
answer
107
views
Is the WolframScript error message "The product exited because of a license error" accurate?
I find that sometimes when I use wolframscript to run a .wls file
(as part of a workflow involving hundreds of such files),
its ...
0
votes
1
answer
55
views
Generate all commutators and anti-commutators up to a certain order of a list of matrices
I am given a list of matrices. At first order I want to evaluate the commutators and anti-commutators of all pairs in the list and return a new list that contains two lists: one containing all ...
0
votes
0
answers
34
views
NDSolve and GeomagneticModelData [closed]
I am trying to use GeomagneticModelData in NDSolve. My code is long and complicated, but here is an artificial example that illustrates my question:
...
0
votes
1
answer
78
views
Plot a surface between three intersecting curves using 3D data sets
I would like to plot a surface between the intersecting points of three 3-dimensional curves. The curves are created using ListLinePlot3D, from the following lists:
List1:
...
3
votes
0
answers
73
views
Crumpling up a line: how to tell if a Line self intersects?
I'm crumpling up lines by rotating them at random positions. That is I take a line, a random rotation angle, and a random pivot point, then every point beyond that gets rotated about the pivot by the ...
1
vote
0
answers
59
views
(N)Solve does not solve a linear system of $2l+1$ variables for $l\geq17$
(MMA v. 14.0, and 13.0)
This is a strange behaviour I encountered when trying to determine Fourier coefficients in the most naive way:
...