All Questions
88,857
questions
0
votes
0
answers
28
views
Why can e^x be plotted but not xe^x? [closed]
Plot[e^x, {x, -1, 10}] produces a plot while Plot[xe^x, {x, -1, 10}] only draws axes.
Can someone please explain why there is no ...
- 43
0
votes
0
answers
35
views
How get this kind of group opener?
Some notebooks of mine have Section (and Subsection) cells formatted like the following, so that clicking on the icon to the right of the Section's title opens the entire group of cells in that ...
- 11.6k
2
votes
2
answers
36
views
Remove sublists with duplicate elements within
I have this list
DeleteDuplicates[Sort[#] & /@ Tuples[Range[4], 3]]
which gives me
{{1, 1, 1}, {1, 1, 2}, {1, 1, 3}, {1, 1, 4}, {1, 2, 2}, {1, 2, 3}, {1,
2, 4},...
- 426
1
vote
1
answer
42
views
FunctionPoles with arbitrary undefined function
Good day everyone. I have very simple question about behaviour of the functions FunctionPoles, FunctionMeromorphic e.t.c. Can these functions work properly with undefined functions? For example when I ...
- 23
2
votes
1
answer
36
views
PlotLegends does not work with StringPadRight?
I'm trying to create a plot legend where the rows contains multiple items, and those items have the same width, so that they appears to be in column.
It should work with String Pad Right but for some ...
0
votes
0
answers
40
views
Drift-diffusion ODEs with two boundary conditions
I am trying to solve drift-diffusion equatons (Poisson's equation, continuity equations for electrons and holes and Kirchhoff's equation) for a reversely biased diode in a stationary state (no time ...
- 53
4
votes
3
answers
80
views
Adjust graphs inside GraphicsRow to be the same scale?
I want to draw a picture with GraphicsRow function in Mathematica. A simple example shows as follows
...
- 229
-1
votes
0
answers
28
views
General solution for X in trapezoid 90 degree [closed]
Could you please help to find a general solution for X, no matter if a > b or a < b ?
[]https://i.stack.imgur.com/dDUEf.png[1]
Thank you!
1
vote
1
answer
68
views
How to place several plots side by side?
I want to place multiple MatrixPlot results side by side. Here's the example code:
...
- 229
3
votes
2
answers
49
views
0
votes
0
answers
16
views
0
votes
1
answer
52
views
How to switch Tan[x] for Sin[x]/Cos[x] without Mathematica changing the latter for the former?
When I ask Mathematica to do this:
(Sin[2 x] - Tan[2 x])/x^3 /. Tan[x_] -> Sin[x]/Cos[x]
It makes no change because Mathematica interprets ...
- 5,061
0
votes
1
answer
16
views
Nested RowBox in MakeExpression reports error when I define my own curl operator, but the single RowBox in MakeExpression works well
I want to define my own vector notation so that the input \[Del] \[Cross] a outputs curl[a] while the ...
- 1
4
votes
2
answers
99
views
How to wrap text of large headings in dataset?
I am trying to achieve the following effect produced in Excel in Wolfram Dataset:
The following attempt doesn't work:
...
- 8,707
1
vote
0
answers
18
views
Periodogram and frequency
On the x axis of periodogram, one should have either a period or frequency. What frequency is used in Periodogram --- angular or ...
- 3,486
0
votes
1
answer
61
views
Is it possible to ask Mathematica to find those points $(x,y)$ at which the given function may reach its global/local extrema?
I have this two-variable function $f(x,y)$ for {x,-Pi,Pi} and {y,-Pi,Pi} in which $\{a,b,c\}$ are real parameters (can be ...
- 93
0
votes
0
answers
25
views
Kernel crash during Interpolation
I have a kinda large code of a solver, and after somewhat random amount of iterations it causes Kernel to shutdown with a "pop" sound and no messages. I tracked the exact line that caused it,...
- 837
0
votes
0
answers
26
views
Plotting a PDF with discrete non-integer values
I can plot the PDF of a continuous distribution like so
d0 = NormalDistribution[0, 1]
Plot[PDF[d0, x], {x, -3, 3}]
I can plot the PDF of a discrete distribution ...
- 111
2
votes
2
answers
59
views
Access item of multidimensional table
I am working on an program that uses a parametric dimensions table created like this:
t = Table @@ Prepend[{2, 3, 4, 5}, 0]
No problem to get the value of a given ...
- 339
1
vote
1
answer
45
views
A 3-dimensional principal value integral [closed]
I am trying to find a principal value integral of the following form in Mathematica. $f(z)$ is a smooth function. The problem is that Mathematica is very slow in this computation.
$\int_1^2 dx\int_1^3 ...
- 51
3
votes
2
answers
190
views
How to Vectorize this Function?
I have been puzzling over how to vectorize the following function:
...
- 339
0
votes
0
answers
30
views
PDE Problem: NDsolve give the results inconsistent with the initial state [duplicate]
We are solving the non-linear PDE, like this
...
- 177
1
vote
1
answer
41
views
How to concatenate an array of matrices?
When trying to concatenate matrices i usually use Join. But having the matrices in an array it gets tricky.
As an example:
...
- 117
0
votes
0
answers
37
views
Fitting an exponential system
Consider the following system over a periodic array, where $1\leq j\leq n$,
$$
y_j= \sum_{k=0}^m \frac{e^{-\sum_{|i|\leq k}(k-|i|)x_{j+i}}-e^{-\sum_{|i|\leq k}(k+1-|i|)x_{j+i}}}{\sum_{|i|\leq k} x_{j+...
- 4,362
0
votes
0
answers
30
views
How to reassign variable value? [closed]
I wrote this code for metric ={{1,0,0},{0,1,0},{0,0,1}} but then changed the metric. However, the value of the metric in christ ...
0
votes
1
answer
19
views
AceGen/AceFEM: Divergence in a term, that should be equal to zero
I have a problem concerning the order of the evaluation of the AceFEM parameters.
My AceGen Element contains, among many others, an expression of the form
B (aa - bb/(cc Exp[dd w^2] + ff))
with B, aa, ...
1
vote
1
answer
40
views
Understanding Distribute when applied with a user defined function
I would expect this
F[x_] := Module[{aux = x}, aux = X];
{a + b + c, e+ f} // Map[Distribute@*F]
to yield
{3X, 2X}
instead, the function is not distributed ...
- 670
0
votes
1
answer
33
views
Doing algebra with differential operators
I'm doing some work on stochastic processes, where I use random functions which are defined by their properties over averages, i.e $$\langle f(t) \rangle =0 \\ \langle f(t) f(t')\rangle = \alpha(x,y) ...
- 1
0
votes
0
answers
28
views
Notebook contents replaced with Null
I opened a notebook that I had recently made only to discover that all cells except the first one (an initialization cell) have been removed and all titles/subtitles except the first one have been ...
- 1,216
1
vote
1
answer
32
views
Using Replace with
I have an expression
expr=Derivative[1][A][\[Zeta]] + Derivative[2][A][\[Zeta]] +
Derivative[3][A][\[Zeta]] + Derivative[4][A][\[Zeta]]
I want to replace ...
- 367
1
vote
1
answer
58
views
Pull out numerical factors from the argument
I'm trying to define a function that is distributive over Plus and pulls out the numerical factors from the argument:
...
- 670
0
votes
0
answers
21
views
Help with Mathematica Documentation Installation Error
I've encountered an error while installing the documentation for Mathematica, as displayed in the image below. Although the file that the software is asking for is clearly visible and unrestricted, ...
- 2,822
0
votes
3
answers
89
views
How to plot the solutions of nonlinear equations with a parameter varies?
I want to get the solutions of equations with a parameter. But I cannot get a closed-form expressions of x、y. I just want to show how x、y vary with the parameter [Delta]. If i assign values to [Delta],...
3
votes
2
answers
94
views
Efficient method (maybe parallel method) to calculate a 256$\times$256 matrix?
I want to calculate a matrix of shape 256$\times$256 as follows
...
- 229
2
votes
3
answers
184
views
How to verify the ODE for Airy function with Mathematica?
I believe that the function AiryAi[x] satisfies the ODE y''[x]-x*y[x]==0
(see Encyclopedia of Mathematics and
Wiki and
Weisstein,...
- 21.1k
4
votes
1
answer
32
views
TimelinePlot with many intervals becomes white
This is an example of a TimelinePlot with 100 intervals:
TimelinePlot[Table[Interval[{0, 1}], {30}],
PerformanceGoal -> "Speed"]
If we ...
- 7,848
6
votes
1
answer
119
views
Distinguish three fraction forms (feature stronger than Hold)
This question can not be typed easily, using mathematica stackexchange interface.
So here is a GIF file :
My question is : Can we construct a function f whose ...
- 3,623
1
vote
0
answers
19
views
Incorrect result for parallel run to calculate a Do loop? [closed]
I want to calculate the following Do loop
Clear["Global`*"];
pmat = ConstantArray[0, {4, 4}];
ParallelDo[pmat[[i, j]] = i*j, {i, 1, 4}, {j, 1, 4}];
pmat
...
- 229
-1
votes
0
answers
18
views
Mathematica plot function of this [migrated]
Descriptive function of motion of a rigid rod around an axis and, by analogy, around a cylinder and the volume "swept" from it
I kindly ask for your help for the "rust" that, after ...
- 1
1
vote
1
answer
43
views
Fourier series solution for Laplace equation in polar coordinates results in Power::infy and Infinity::indet
Definition of function f
f[θ_] = 1 + Cos[2 θ] + Sin[3 θ]
Plot[f[θ], {θ, 0, 2 π}]
Computation of the Fourier coefficients
...
0
votes
1
answer
38
views
`Periodogram` returning only 1/0 error
I have a large dataset and would like to get a Periodogram (I saved the data as CloudObject):
...
- 3,486
3
votes
2
answers
108
views
Partition of lists with specified elements
I have an array like this and want to split it into sublists. It should contain the first element "Res" without curly braces and the one sublist starts from 2 to the 9th column the 3rd ...
- 73
3
votes
2
answers
101
views
Cube inscribed into a dipyramid
Starting with code nicely done at this post, I have been able to produce this graphic
Several problems remain:
For Dipyramid, there is a superfluous line through the center of the cube. There are two ...
- 714
0
votes
0
answers
38
views
Creating Common Color Scheme and Contour Intervals Across Different Data Sets
With the help of @JimB in Comparing different ListPlot3D outputs between different data sets I have a code that will plot the difference between two mesh maps (shown in the code below). However, I ...
1
vote
0
answers
46
views
Does anyone have any Mathematica code for rainflow counting for fatigue and damage equivalent load anlaysis?
‘Rainflow Counting’ is a method to determine the number of fatigue cycles present in a load-time history. See https://en.wikipedia.org/wiki/Rainflow-counting_algorithm
There is a MatLab function that ...
- 63
1
vote
0
answers
77
views
Solution to a 2D Schrödinger equation
I am trying to solve a 2D Schrödinger equation with a complicated non-separable potential $V(z,\rho)$,
$$ \nabla^{2}\Psi(z,\rho) +2(E_{0}-V(z,\rho))\Psi(z,\rho),$$
where $E_{0}$is the energy, $\hbar=m=...
- 11
0
votes
0
answers
44
views
Stuck in parallel computing [closed]
I'm running ParallelTable using Mathematica, and it always stuck!
The following errors:
LinkObject::linkd: Unable to communicate with closed link
LinkObject["/...
- 31
0
votes
0
answers
36
views
Cubic Bezier Curve is not plotting correctly in Wolfram alpha [closed]
I'm trying to plot a cubic bezier curve to understand if the equation is correct. I have the following equation, which has set p0..p3 to 0.5, which should result in a linear curve.
...
- 101
2
votes
1
answer
80
views
Partion of lists
I have a list like this and want to split it into three sublists. One should contain only the first element the 2nd should contain 8 elements starting from 1.944 to 11 and the third should start from ...
- 73
1
vote
1
answer
41
views
