All Questions
93,916
questions
7
votes
3
answers
378
views
1
vote
1
answer
86
views
Robotic Appendages in MMA
I am trying to animate a generalized abstraction of robotic appendages (arms, hands, legs) in Mathematica where the translation is "smooth" in the sense that all of the points except for the ...
- 18
0
votes
1
answer
23
views
How to simplify and expression subjected to constraints?
It is possible to simplify the following expression
...
- 23.5k
0
votes
0
answers
10
views
How define a composition of operators?
If I define P[x]=D[#,x]& (derivative operator)
How can I defines another operator $Q$ such that $Q(f(x))=Pf(x)+a$ (for example)?
Thanks.
- 203
1
vote
2
answers
109
views
The problem of finding the maximum coefficient term in the Binomial expansion,Find the value range of K
The problem is shown in the figure, and the result should be the range of K obtained at the end of the image
...
- 4,063
0
votes
1
answer
94
views
How to arrange the Polynomial according to the descending power of x?
the Polynomial is follows：
xpoly=-a^2 b^2 + (b^2 + a^2 k^2) x^2 + a^2 k^2 x0^2 - 2 a^2 k x0 y0 +
a^2 y0^2 + x (-2 a^2 k^2 x0 + 2 a^2 k y0)
How to get the results ...
- 4,063
0
votes
1
answer
34
views
How to solve differential equation with small values
I want to solve this system of differential equations with Mathematica:
...
- 143k
3
votes
5
answers
356
views
How to Find Duplicate Sets in a List
Given the list below, I would like to find the sets within that list that are identical according to the order of their elements, generate that set, and show the number of times it appears in Lst. For ...
- 23.9k
0
votes
2
answers
78
views
Z - filter - RSolve vs InverseZTransform for unit state response : RSolve gives an incorrect result, where is my mistake?
I want to compare the unit step response of a z-filter given by two different methods:
InverseZtransform,
RSolve.
...
- 4,387
1
vote
4
answers
50
views
How to combine multiple pure conditions with an AND operator?
I have a list of Pure conditions {con1[#]&,con2[#]&,con3[#]&} and want to combine them in one Pure Function ...
- 68.9k
0
votes
0
answers
24
views
Interpolation and polynomial approximation
Does anyone know how to solve these requests in Mathematica?
Let the function f(x) be given with nodes (0,-4), (1,-3) and (3,5). To compose a Lagrangian interpolation polynomial of the second degree.
...
9
votes
3
answers
388
views
Does anyone know what is this number?
Answering this question, @user64494 came with a very nice answer.
My problem is that the front factor is
HypergeometricPFQ[{1/2, 1/2, 1, 1}, {3/4, 5/4, 3/2}, -1]
...
- 36k
205
votes
15
answers
75k
views
Elegant operations on matrix rows and columns
Question
The Mathematica tutorial has a section 'Basic Matrix Operations', describing operations like transpose, inverse and determinant. These operations all work on entire matrices. I am missing a ...
- 69.7k
0
votes
0
answers
35
views
JacobianMatrix function flattens input in column order
The JacobianMatrix function appears to flatten its input in column order. Both of the following queries (Wolfram Alpha syntax) give the same result:
Q1: "JacobianMatrix of {{a_1+a_2, a_1+ a_2, ...
- 1
4
votes
3
answers
87
views
Using Select with a function on 3d Table
From the following 3d-Table
t1={{{1, 1}, {2, 1}, {3, 4/3}}, {{1, 0}, {2, 1/2}, {3, 1}}, {{1, -1}, {2,
0}, {3, 2/3}}}
I want to ...
- 23.9k
8
votes
5
answers
483
views
Selecting numbers from a list
If I wish to select numbers which are greater than 2 or less than 1, I use
the following codes respectively:
...
- 23.9k
2
votes
1
answer
42
views
Solving a bad-behaving equation with shooting method
I would like to numerically solve
$a^2\frac{d}{d\sigma}[(1+A_tQ)\frac{d\psi}{d\sigma}]=\psi(1+A_tQ-a\Phi\frac{dQ}{d\sigma})$
where $Q(\sigma)=\frac{2}{\sqrt{\pi}}\int_0^\sigma exp(-x^2)dx$.
$a$ and $...
- 44.5k
-1
votes
0
answers
28
views
Solving first order DE for the case has a singularity r0 and plot it and see the singuarity
I would like to solve and plot this around r0 but it is not working?
...
- 26.4k
6
votes
9
answers
398
views
Substitute an element X in a list with 0.5*X
I have a list with 33600 Elements and I have to replace every element bigger than 6000 with its half. I "practiced" with a smaller list and tried the following:
...
- 23.9k
0
votes
3
answers
65
views
Get transformation matrix from transformations
I want to find a matrix corresponding to certain transformations I already know. Basically I have a set of vectors $x_i$ and I need the matrix $m$ that transforms $x_i$ to another set of vectors $b_i$ ...
- 47.5k
3
votes
5
answers
88
views
0
votes
0
answers
27
views
Patterns with Dot [duplicate]
I would like to understand the behavior of Dot to build patterns with it. Could someone tell me what is going on in these examples?
...
- 988
2
votes
1
answer
32
views
Trouble installing the package MultipleZetaValues
I have tried to install the package MultipleZetaValues using
...
- 24.8k
0
votes
3
answers
82
views
+50
Properly define function from outcome of NSolve and FindRoot
We have the function $\gamma(u,v)$ defined implicitly as the solution of
\begin{align}
\sin\gamma(u,v)=g\left(u-v\cos\gamma(u,v) \right),
\end{align}
being $g$ a given function. I can solve for $\...
- 2,777
6
votes
3
answers
447
views
Selecting points within a circular region from a 2D scatter plot
I have a 2D scatter plot. I want to define a circular region in this plot and use the data points inside the circular region for further analysis.
Is there any way to do this and plot the two set of ...
- 53.8k
1
vote
0
answers
29
views
How to decrease the computation timing while using NIntegrate?
I'm trying to calculate the $A$ and $F$ values by using this code,
...
- 2,233
4
votes
2
answers
179
views
Is it possible to have the asymptotics of this function?
Working the problem of
$$I_n=\int_0^1 \frac{\tan ^{-1}\left(x^n\right)}{\sqrt{1-x^n}} \, dx$$ which I have not be able to compute with Mathematica. A tedious work gave the result
$$I_n=\frac{\sqrt{\pi ...
- 6,727
3
votes
1
answer
105
views
Phase portait for orbits of maps in 1D
I am looking for a way to generate the phase portrait on the real line of the orbits of maps, such as
$$f(x)=-x$$
which orbit has the phase portrait :
Then another example:
$$g(x)=2x$$
has an orbit ...
- 603
3
votes
2
answers
116
views
How to modify PlotTheme->"Marketing"?
The code is lent from this and later modified as per need, as shown below:
...
- 395k
0
votes
1
answer
187
views
Issue with threading matrices
I like this answer, which provides an "autoThread" function for more intelligent threading, but it doesn't work in this example and was hoping for a fix.
So for this code:
...
CommunityBot
- 1
-2
votes
1
answer
52
views
Using Mathematica to calculate matrix multiplication [closed]
egg [1; 2; 3].*[1 2]=[ 1 2; 2 4; 3 6] (easy by use Matlab),I cannot use Mathematica calculate this. {{1},{2},{3}}.{1,2} is wrong.
- 26.4k
0
votes
1
answer
203
views
NDSolve unable to find initial conditions that satisfy the residual function within specified tolerances
I'm trying to solve a set of differential-algebraic equations with boundary conditions:
$A\frac{d^2\psi}{dx^2}=[c_{F}-2c_{D}(x)+c_{C}(x)]F$
$c_{D}(x)=0.1\exp(-0.2253 - 76.5596\psi(x) - 1.1149)$
$c_{C}(...
CommunityBot
- 1
3
votes
3
answers
825
views
Integrate on a contour in the complex plane
I want to integrate the function
f[z]= z + Conjugate[z]
over a circle of radius 2 centered at the origin.
For the sake of stating something that I have tried:
<...
- 66.2k
1
vote
2
answers
94
views
Contour integral with radius infinite
How can I get compute a contour integral of the function $f(z)=\exp(i z)/z$ in the upper circle with center in $(0,0)$ and radius $R$? I want verify that $\lim_{R\to \infty}\int_C f(x)=0$ in ...
- 22.9k
5
votes
2
answers
306
views
Direct Import Remote File via SSH without Copying in Windows
Is there any option to directly import to a Windows-driven Mathematica kernel a file from a remote server without copying it on hard drive? Right now I'm using ...
- 26.7k
5
votes
0
answers
51
views
Early computer art - Frieder Nake's "Walk Through Raster"
Frieder Nake
Frieder Nake (born 1938 in Stuttgart, Germany) is a mathematician, computer scientist, and pioneer of computer art. Nake is one of the "3N" computer pioneers, an abbreviation ...
- 69.7k
1
vote
2
answers
204
views
Setting up a PDE for a time-independent Schrödinger equation
I am trying to solve a 2d Schrödinger equation with a non-separable potential because I want to calculate the probability of reflection for different angles of incidence of a plane wave.
Here I ...
CommunityBot
- 1
1
vote
2
answers
88
views
RecurrenceTable vs For loop : they do not give the same results. Why?
I have a second-order recurrence equation that I want to plot.
I've used two different methods.
The first uses RecurrenceTable, the second uses a traditional ...
- 66.2k
1
vote
2
answers
58
views
How can I get a simpler way to draw a solid?
Let two circles center $O_1$, radius $10$ and center $O_2$, radius $6$ so that $AB$ is a diameter of the circle center $O_2$. I am trying to draw solid when rotate the filled region around line $...
- 72.8k
6
votes
2
answers
248
views
How can I draw solid when rotate this rigion around Ox axis?
I have this picture, knowing that $AC=2$. The point $B$ is midpoint of $AC$, $D$ is intersection point of the semicirle and arc center at $B$ and radius 1. I want to rotate the region with gray fill ...
- 72.8k
1
vote
2
answers
44
views
Is it possible to "save/convert" a 3D plot into a FBX or OBJ file to use in softwares like blender or maya?
Suppose you run a code to plot:
ContourPlot3D[
x^3 + y^2 - z^2 == 0, {x, -2, 2}, {y, -2, 2}, {z, -2, 2}]
or
...
CommunityBot
- 1
1
vote
1
answer
55
views
How do I modify all the list elements as patterns
Is there any easier way to change all the list elements as elements with patterns?
Here is an example:
list={a,b,c,d}
I want to transform it as a list of patterns ...
- 69.7k
2
votes
3
answers
83
views
Locate all row and column pairs containing a value in a table
I would like to find all row and column pairs that contain 1 in a table. For example, the row and column pairs that contain 1 in the table are (a,b),(b,a),(b,c),(c,b),(c,d),(d,c),(d,e),and (e,d).
<...
- 69.7k
5
votes
3
answers
144
views
Removing a nested list associated with a key and inserting into a new list
I'm trying to remove nested lists that are associated with a key
...
- 69.7k
1
vote
1
answer
67
views
Symbolic Computation - Don't Evaluate Integral
I'm following a paper. I've been trying to get Mathematica to help me. Combining equation 1 and equation 2 should result in equation 3.
Equation 1:
\begin{equation}
R=C k^2 T^2 \int_0^{\infty} \ln \...
- 236k
1
vote
2
answers
62
views
Plotting a vector field on a cylinder
Assume a parametric equation for a cylinder
$$\mathrm{cyl} (\theta, z) = (r \cos\theta, r \sin\theta,z)$$
and a vector field given by
$$\mathrm{vecField} (\theta, z)=\frac{\sin(\alpha)}{r}\partial_\...
- 8,616
1
vote
2
answers
129
views
Problems with diminishing particle diameter and increasing time step for a simulation of volcanic ashes
I am rather new to Mathematica, and I have been tasked with a project to attempt to simulate the trajectory of volcanic ash particles. In the long term, I am trying to simulate particles of diameters ...
- 11
1
vote
1
answer
51
views
EM Wave Equation: Insufficient initial conditions for NDSolve?
I am trying to model a EM wave propagation through a region of free space. However, Mathematica tells that there are insufficient initial conditions, even though I specify all values at ...
- 39.8k
0
votes
2
answers
90
views
How best to 2D plot nearly vertical function regions?
There has got to be some better way of plotting near vertical function values other than the default 2D Mesh. The only specifications that I want to give are the function definition and the horizontal ...
- 717
-3
votes
2
answers
108
views
Which of the ContourPlots is correct?
I'd like to visualize the solution of the system
Reduce[Log[3, a - x^2] == Log[3, a - y^2] &&
x^2 + x^2 == 4 x + 6 y, {x, y}, Reals]
...
- 24.8k