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Split String after a Character

I want to split strings after "." a = {"this si theh jnfdkdkvd/. and then this is . and then this is. \ gjgjdjd. ugddjgd. ddngdjng."} in ...
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0answers
6 views

why did the one without Assumptions in Integrate work while the other one don't?

Here is 2 trials I have already tried. Assumptions in Integrate. Input: ...
1
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1answer
17 views

Last part of a url (after the “/”)

I want the last number after the "/". How can I do that? "http://arxiv.org/abs/math/0208009v1" I just want 0208009v1 I want to import multiple ...
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0answers
23 views

Why are nested anonymous pure functions shielded from evaluation?

I tried the following code (ignoring the warning messages): ...
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0answers
23 views

Confusion about the sorting function

The following one-dimensional array can be sorted well: Sort[{Infinity, 10, 2, 1, -4}, #1 < #2 &] But the following two-dimensional array cannot sort the <...
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0answers
10 views

Asymptotic Relation as Boundary Condition

I want to solve a system of non-linear second order differential equations. For some of the unknown functions there are boundary conditions that i know how to write them in Mathematica. One of the ...
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0answers
28 views

How to write a more concise `RowReduce` function that can deal with symbolic matrix?

I wrote an RowReduce function that can handle symbolic matrices: ...
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1answer
46 views

Keep irrelevant variables outside function arguments

I want to define several functions of variables x,y say ...
5
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1answer
68 views

How to get the progressive application of list of rules?

all. I need some suggestion on this problem. I have a very long list of rules, using this list of rules I want to see how some elements evolve as I successively apply the next rules on the previous ...
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0answers
39 views

Why doesn't Mathematica ComplexExpand integrals?

Consider this code example: ComplexExpand[Re[Integrate[f[t], {t, a, b}]]] Mathematica gives me the result as ...
1
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1answer
55 views

Visualizing an Affine Matrix

I have a computer graphics program that prints out affine matrices like ...
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0answers
42 views

Plot3D lighting issue

Plot3D is giving me very weird lighting. If I run the following line of code from the Plot3D documentation. ...
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0answers
18 views

LU decomposition and power of a matrix [closed]

How to write codes of LU decomposition and power of matrix on Mathematica? Please can you tell me?
2
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1answer
53 views

Mass Transport FEM Using Quad Mesh

This question is a follow-up to my previous question and an attempt to implement @Tim Laska's excellent approach of setting up an anisotropic quad mesh. I'm solving a similar problem to @Tim Laska's ...
2
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0answers
32 views

Scaling the InverseRadon function

I have to calculate a 2-dimensional radially symmetric distribution from a single projection. I know that InverseRadon should actually do the job, but I get the ...
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0answers
23 views

Why are these expressions with shifted delta functions not equal?

I have the following equation Exp[a-t]*DiracDelta[t-a] == DiracDelta[t-a] which cannot be evaluated. However, if I plug in 0 for a: ...
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0answers
38 views

NDSolve and NIntegrate with parameters

I have a problem with a numeric computation. I should solve a numeric ODE and the rhs is a numeric parametric function that I find with several NIntegrate. I'd like ...
2
votes
1answer
43 views

Sorting out polynomials with roots of an undesireable magnitude

I have a list of polynomials polys. I want a set of $f(x) \in$ polys which have roots strictly in $\{S^1,0\}$, with $S^1$ being ...
1
vote
1answer
29 views

Is it possible to make a composite tooltip with multiple data types?

I have a large set of spectral data that requires comparison to training data. I need to provide a simple color difference for each piece of data, Spectral Plots of both the training data and RMSE ...
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0answers
34 views

Fast way using inner row-elements iteration to construct matrix?

I'm trying to construct a matrix which is according to inner last two row-elements. ...
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0answers
40 views

I need advice on which device to get to be able to run Wolfram notebook applications on the go on mobile phones?

I am planning to get a new phone later this month since I have moved to a new country and my old phone is causing me difficulties. I see there are good deals on Samsung (Android) and iPhones (IOS). My ...
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0answers
39 views

wrong syntax in very short package

Here is a very short package ...
0
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1answer
26 views

How to find expansion coefficients in Fourier-Legendre

I am trying to find the coefficients for the Fourier-Legendre expansion of a potential. My goal was to obtain the coefficients as expressions in terms of x and y. I followed the example given on the ...
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0answers
29 views

problem with solving a simple third order differential equation [duplicate]

I just wrote a simple line of code to solve a third-order differential equation: DSolve[{y'''[x] + 4*y[x]==0, y[0]==1, y'[0]==2, y''[0]==0}, y[x], x] Then ...
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1answer
27 views

How to optimize a function with two variables such that the constraint is satisified

I have a hollow bar with outer diameter d1 and inner diameter d2. One end of the bar is fixed and the other is subjected load. ...
1
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2answers
56 views

How to plot a complex functions in complex plane?

How to plot a complex equation like f(z)=z^2 in complex plane? Is it required to separate the real and imaginary parts or it can be done directly ?
1
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0answers
18 views

Solving system of coupled PDEs with method of lines

I'm trying to solve: $\partial _{z} U(z,t) = i \sqrt{d} P(z,t)$ $\partial _{t} P(z,t) = -P(z, t) + i \sqrt{d} U(z,t) + i \Omega_{c}(t)S(z, t)$ $\partial _{t} S(z,t) = i \Omega_{c}(t)P(z, t)$ For the ...
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0answers
29 views

Data set for Neural Network

I am using Regression with Neural Networks and I want to set my train and test dataset. But I have a huge dataset in Excel that obviously do not have the shape that Mathematica requires. If I ...
1
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1answer
37 views

Deriving formulas for continued fraction expansions

A version of a continued fraction expansion of a rational number $r\in \mathbb Q$ is defined as \begin{align} r =[a_0,a_1,a_2,\ldots,a_k]= a_0 - \frac{1}{a_1 - \frac{1}{a_2 - \dots - \tfrac{1}{a_k}}} \...
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0answers
36 views

I have two equation two unknowns, how to find there expression symbolically

I have a two-equation with two unknowns r2 and t. I am trying to solve for them symbolically is it possible? ...
1
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0answers
10 views

How to create a denominator for division in Wolfram Cloud? [duplicate]

How to create a denominator for division, or other math objects like superscript for exponent, in Wolfram Cloud? In Mathematica you have the typesetting/characters window, or you can use Ctrl+/ for ...
0
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1answer
69 views

Why doesn't Mathematica cancel this constant out of the integral?

I have the mathematical expression Integrate[f[r], {r, τ, t}] == a*Integrate[f[r]/a, {r, τ, t}] which is obviously true for all functions ...
0
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0answers
32 views

How can I make a two-dimensional plot for a complex function [closed]

How can I plot an equation involving one complex variable in the $xy$-plane (in two dimensions)? For example, consider Abs[z] <= 4 which is the region ...
0
votes
1answer
30 views

Comparing elements in a list and ignoring white space

I have two lists with element entries. I want Mathematica to identify an element in an opposing list such as Ag107 to be the same as Ag 107 ignoring any space. Each different element occurs only a ...
0
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0answers
14 views

A package that was found in while local directory stops being found when I move it to AddOns [closed]

I'm trying to move a package that was residing in local directory (and was found and worked) to AddOns folder. But, I get an error message ...
2
votes
1answer
109 views

Why sometimes eigenvectors matrix cannot transform to initial matrix?

As we know, $$H=U^{-1}\Lambda U $$ where $\Lambda $ is the diagonal matrix and $H$ is the original matrix, $U$ is the eigenvector matrix. Also, we can restore the original matrix via: $$\Lambda=UHU^{-...
0
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0answers
18 views

Return Link with XML Element

I am trying to import multiple links. I just want the link after ...
0
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0answers
20 views

How to insert text in Table [duplicate]

I have Table[{i^2, "mod", i + 1, "=", Mod[i^2, i - 1]}, {i, 3, 4}] which gives me ...
1
vote
3answers
55 views

How to find the closed loop number of an array

I want to find the minimum number of swaps required to reset an array. This problem has many applications in linear algebra. The key point of this question is to find the number of closed loops in ...
3
votes
0answers
30 views

BoxWhiskerChart features breaking with massive WeightedData datasets

I have huge WeightedData objects (500K) that I am trying to plot in BoxWhiskerChart. I can get the default chart, but if I try and use the "Outliers" option, it breaks and hits a recursion ...
1
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0answers
21 views

How to convolve two audio signal?

Can we obtain reverb effect by convolve two audio signal? Here are some example. https://www.bilibili.com/video/BV1vE411h7W2
3
votes
2answers
137 views

How to divide a list into several single loops

Because of some problems, I need to divide the permutation represented by a list into several single loop lists. For example, for list {4, 3, 2, 1, 7, 6, 5}, it can ...
0
votes
1answer
39 views

Construct a matrix from blocks of matrices

I am trying to find eigen values of a matrix system where entries of the matrix are also matrix. This is how my matrix looks: $$ M=\begin{bmatrix} H[j,j] & T[j,j+1] & 0 &0 &....
0
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1answer
35 views

Overlay for two axes plot

I have these two plots that I want to merge in order to create a plot with two axes. I just want to translate the second plot in order for them precisely coincide. However, it seems that the Translate ...
1
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0answers
25 views

Generating a list of the degree-$n$ Kronecker polynomials

A Kronecker polynomial is a polynomial such that Its coefficients are integers, Its roots are on the unit circle or $0$, Its leading coefficient is $1$. From here, there are finitely many Kronecker ...
3
votes
1answer
63 views

Problem using PlotMarkers -> “Sphere” in a DiscretePlot3D

I am trying to make a DiscretePlot3D of a DiscreteUniformDistribution but the result in not the expected. I tried to use the PlotMarker-> "Sphere" but the spheres appear flattened. With ...
1
vote
1answer
66 views

Symbolic solution to periodic boundary conditions

Is it possible to get an analytical solution to the following problem? If so, how? $$a w^{(1,0)}(x,t)+b w^{(0,1)}(x,t)=p(x)+g w(x,t)$$ $$I.C.: w(x,0)=0 | B.C.: w(0,t)=w(1,t) | x \in \left[0, 1\right]$...
0
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0answers
21 views

Solve::nsmet error message while trying to find symbolic solution for equation

I would like to solve several equations for x and I'm looking for symbolic solutions. The later ones might have some rather difficult or no result at all, but I ...
0
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0answers
116 views

Cycle detection with Mathematica

Suppose we have cellular automaton on a network. For simplicity, we will use matrix notation. ...
2
votes
2answers
65 views

Computational efficient way to find a SL(2,Z) matrix between two set of vectors

Suppose I have two sets of vectors (let's say it 2d, but it would be nice to generalize it to arbitrary dimensions): $(v_1,v_2,\ldots,v_n)$ and $(v'_1,v'_2,\ldots,v'_n)$ and they have integer entries, ...

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