Questions tagged [matrix]

Questions on the manipulation of matrices in Mathematica.

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How to optimally defragment the colors? [closed]

This is a matrix plot with randomly selected colors. I like to defragment the colors to create an optimal grouping of cells with the same color. ...
Tugrul Temel's user avatar
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5 votes
2 answers
100 views

Finding a basis of positive vectors in the kernel of a matrix

The kernel to the left of the matrix ...
florin's user avatar
  • 1,642
4 votes
1 answer
151 views

How to plot the elements of a matrix in {x,y,z} coordinates?

I have the {x,y,z} positions of a fullerene and after connecting the first neighbors with ~1.37 and 1.45 distances in the matrix B as the following ...
Lucas Lopes's user avatar
0 votes
0 answers
78 views

The multiplication result is not written as a number [closed]

This is my code: ...
j.doe's user avatar
  • 123
1 vote
2 answers
98 views

How to construct a custom-made matrix conditional on a set of rules?

The following code does what I intend to achieve; however, it is too cluttered for a simple matrix operation. I like to reduce the code to a one-line code as a ...
Tugrul Temel's user avatar
  • 5,508
0 votes
0 answers
40 views

Matrix Dimension Changes [closed]

I am trying to run the following code: ...
Lelouch's user avatar
0 votes
1 answer
42 views

'The objective function is not a scalar' in NMinimize

I am trying to do a GMM(Generalized Method of Moments) by NMinimize, it comes up with the warning 'The objective function is not a scalar', here's what I have tried:...
Lomath's user avatar
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12 votes
6 answers
2k views

The Battleship game: Identify objects within a matrix

Toy data ...
eldo's user avatar
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2 votes
3 answers
78 views

Convert a string with $N^2$ entries to a rank-$N$ matrix

Suppose we are given a set of numeral data like a string that consists of $N^2$ entries, say $N$ is very large (here $N=8$ for simplicity, but $N$ can be $10^8$...) ...
zeta's user avatar
  • 121
0 votes
0 answers
78 views

Output a 24 by 24 Leech lattice

Input a rank-8 $E_8$ lattice, $$ M_{E_8}=\begin{pmatrix} 2 & -1 & 0 & 0 & 0 & 0 & 0 & 0 \\ -1 & 2 & -1& 0 & 0 & 0 & 0 & 0 \\ 0 &...
zeta's user avatar
  • 121
0 votes
1 answer
89 views

Symbolic matrices

How does one declare a matrix of specific symbolic dimension? For instance, if $A,B,C,D$ are four $n\times n$ matrices, $M$ is the block matrix $$ M=\begin{bmatrix} A & B \\ C & D \end{bmatrix}...
Cryme's user avatar
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2 votes
0 answers
65 views

Giving MatrixPlot coordinates [closed]

I am using MatrixPlot for plotting the following array ...
Tanmoy Pati's user avatar
7 votes
4 answers
505 views

Fill an empty matrix with the depth of its elements

Given an arbitrarily nested empty matrix like for example mat = { {}, {{}, {}}, {{}, {{}}, {}}, {{}, {{}}, {}, {{{}}}} }; and knowing that ...
eldo's user avatar
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2 votes
0 answers
66 views

Performance of multiplying two identity matrices

I am running Mathematica 13.3.1.0 on a M1 Mac, and I ran the following codes to check on the time spent on matrix multiplication. ...
Lelouch's user avatar
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3 votes
4 answers
365 views

Eigenvectors are divided by zero depending on evaluation, 6x6 matrix

I calculated the Eigenvectors of the $6\times 6$ matrix $m$ with parameters $(a,b,c,d,e,f)\in \mathbb{R_{\ge 0}}$. If I set e.g. $b\rightarrow 0$ after calculation, then 4 of the 6 Eigenvectors are ...
granular bastard's user avatar
4 votes
3 answers
434 views

Eigenvectors are divided by zero depending on evaluation, 4x4 matrix

I calculated the Eigenvectors of the $4\times 4$ matrix $m$ with parameters $(a,b,c,d)\in \mathbb{R_{\ge 0}}$. If I set e.g. $b\rightarrow 0$ after calculation, then some of the Eigenvectors are ...
granular bastard's user avatar
1 vote
2 answers
109 views

How to plot a matrix with this 3D style in a bar chart?

Reading the paper Measuring Wigner functions of quantum states of light in the undergraduate laboratory in arXiv, I found the figure above, whose style is very beautiful. I tried to reproduce it, but ...
gang liu's user avatar
2 votes
1 answer
89 views

Solving a Lindblad differential equation in matrix form

I am trying to solve the following Lindblad equation analytically with Mathematica: $$\frac{d\rho}{dt}=-i[H,\rho]+\sum\nolimits_{i=0}^1 K_i\rho K_i^+-\frac12\cdot\{K_i^+K_i,\rho\},$$ where $$H=\begin{...
QC_Pod's user avatar
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0 votes
0 answers
28 views

Sparse Kronecker Product of Pauli Matricies

Suppose I have a list of Pauli matrices (X, Z and I type) paulis = {x,z,z,i,z,x,i,z}; I would like to compute a sparse array equivalent to $$x \otimes z\otimes z \...
user2757771's user avatar
1 vote
3 answers
192 views

How to implement tridiagonal matrix algorithm?

I have created the tridiagonal matrix below: ...
Mule's user avatar
  • 43
0 votes
0 answers
59 views

Plotting list of points to a special graph

Given Mathematica code of eigenvalues in different variable-paths , I want to add experimental data in the path Gamma-X ; X-Gamma ; and M-Gamma . Here is the code : ...
Med Ch's user avatar
  • 117
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0 answers
29 views

How to extract subscripts in mathematica and apply a function on them?

For a bit of context, I am trying to evaluate an integration over Haar randm unitaries. I couldn't find any inbuilt function, so I am trying to implement a simple code for the Wingarten functtion in ...
Endeavour 's user avatar
0 votes
1 answer
81 views

Eigenvalue Problem - Nullspace Basis

I need to solve an eigenvalue problem where some of the eigenvalues are 0. Due to the fact that I just need the eigenvectors associated to the 0-eigenvalues in some cases I'd just like to calculate ...
mathetronaut's user avatar
6 votes
4 answers
650 views

Find a certain path through a matrix

I would like to get a functional solution and nice display form for the following problem: 1. Example data ...
eldo's user avatar
  • 48.9k
1 vote
1 answer
83 views

How to calculate maximum between two or more lists element by element and also the index corresponding to the maximum element?

I am looking for a function say f such that for example f[{a1,b1,c1},{a2,b2,c2}] will give {Max[a1,a2],Max[b1,b2],Max[c1,c2]} and also a function g say such that g[{{a1, a2, a3}, {b1, b2, b3}},{{c1, ...
Georgy's user avatar
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2 votes
1 answer
66 views

Efficient ways to generate a matrix from multiplying two elements of some matrix

I am working on the single particle entanglement entropy and in the process I have something like ...
wooohooo's user avatar
  • 279
0 votes
0 answers
91 views

Solve does not find solutions to large equation rotation matrix

I've been seeing some posts already where people mention Solve needs a bit of help to get things solved in some scenarios. I have been trying to figure out the solutions for equations. For the XYZ ...
Jose's user avatar
  • 1
1 vote
1 answer
123 views

Using "Table[]" to create a matrix without submatrices [duplicate]

I'm trying to create a certain 6x6 matrix using Mathematica's in-built "Table[]" function and have landed on ...
ConfusedCabbage's user avatar
5 votes
4 answers
112 views

Interpolation of missing matrix values

Problem statement I want to replace missing matrix values, denoted by an integer 0, with the Mean of their surrounding values. ...
eldo's user avatar
  • 48.9k
7 votes
8 answers
785 views

How can I expand a matrix and fill in zeros?

Given a square matrix like m = {{1,2,3},{4,5,6},{7,8,9}}; I want to expand it to a 5x5 matrix ...
Phillip Dukes's user avatar
2 votes
0 answers
67 views

Elegant operations on associations and datasets

As a useful extension of this question: Elegant operations on matrix rows and columns I would like to ask: What are for you elegant, short, useful or frequently used functions to use with ...
eldo's user avatar
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2 votes
1 answer
113 views

Simple subtraction of two square matrices giving strange results [closed]

I'm new to Mathematica, and I'm writing a function to calculate a complicated pdf. I'm having trouble doing something very basic, subtracting one square matrix from another. I've reduced my problem to ...
mockle's user avatar
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0 votes
0 answers
43 views

On MacOs, I cannot use Needs["QDENSITY`Qdensity`"]

I am trying to get Needs["QDENSITY`Qdensity`"] from (https://library.wolfram.com/infocenter/MathSource/5715/), however, it failed and I get this error: ...
Xui Lao's user avatar
0 votes
1 answer
85 views

How to incorporate boundary conditions?

I have this linearized PDE problem: $$\lambda a^\ast+\bar{a}v^\ast_z+\bar{a}_zv^\ast+\bar{v}a^\ast_z+\bar{v}_za^\ast=0$$ $$\lambda \bar a h^\ast -\bar a \bar h v^\ast_z-\bar a \bar v_z h^\ast - \bar h ...
Fun123's user avatar
  • 47
-1 votes
1 answer
59 views

Make a table in matrix form to display the values of x and y if y =sin[x] and x takes on the certain values [closed]

Don't understand how to do this, tried plugging in "if" statements but my commands won't go through. Extremely new to Mathmatica
Danewd98's user avatar
0 votes
0 answers
45 views

Matrix subtraction not working [duplicate]

I am using Mathematica to solve a hw question. I have the following code: ...
zaza sea's user avatar
1 vote
4 answers
302 views

How to observe transition pathway of a stochastic matrix?

Given a stochastic matrix, m, I like to observe the transition path converging to the limiting distribution. ...
Tugrul Temel's user avatar
  • 5,508
3 votes
4 answers
447 views

Find the shortest possible unique keys

1. Problem statement Given a certain rectangular matrix I want to scan its rows from left right to find equally sized sequences. These sequences should be as short as possible and unique, so that they ...
eldo's user avatar
  • 48.9k
5 votes
4 answers
320 views

Show positions of duplicated matrix elements

1. Problem statement I want to replace duplicated elements within a matrix with a placeholder value. 2. Example data ...
eldo's user avatar
  • 48.9k
3 votes
0 answers
76 views

Mathematica's definition of cos(kA) where A is the 1st Pauli spin matrix [closed]

For a homework assignment I was asked to derive the formula of $e^{ik\sigma_{1}}$ - where $\sigma_{1}$ is the Pauli spin matrix {{0,1},{1,0}} - using the Taylor ...
Raketenmensch 's user avatar
3 votes
2 answers
189 views

Sort sequences by their "randomness"

Example matrix (rows always have equal lengths) ...
eldo's user avatar
  • 48.9k
1 vote
0 answers
86 views

Using Mathematica to find the eigenvectors

I would like some clarification about solving for eigenvectors in Mathematica. I am looking at the following matrix: \begin{equation*} L = \begin{pmatrix} 0 & m(1+\frac{kmwr}{\lambda}) \\ q(1-kpx)...
Sprog's user avatar
  • 179
1 vote
0 answers
69 views

Solving a linear algebra problem containing minimal polynomial degree

Consider a set of three-dimensional points ${\left\{{\left(a,ab,abc\right)}~\middle\vert~a,b,c\in\mathbb{N_+}\land a+b+c\leqslant2023\right\}}$. If there exists a non-zero real polynomial $\...
user688486's user avatar
0 votes
0 answers
60 views

Don't understand reasons for error messages when trying to get elements of matrix

I am trying to simplify the seemingly very complicated inverse of a 4x4 matrix. "Simplify" resulted in something only somewhat less complicated. So yesterday I started simplifying the ...
Alan's user avatar
  • 11
0 votes
0 answers
37 views

Root function in the output [duplicate]

I was calculating the eigenvalues of a matrix and the output contained some eigenvalues like: ...
M Shehzad's user avatar
1 vote
1 answer
152 views

How can I get the determinant of an 8x8 matrix in a particular form?

I would like to get the determinant of a 8x8 matrix with symbolic representation to a particular form. When I used determinant and fullsimply to answer was too long and did not match the form I was ...
Angad Singh's user avatar
0 votes
0 answers
72 views

How do we convert the minimum of two values into its actual result?

I am writing a code in Mathematica where the entries of the matrix depends on the minimum function, which is a function of the position in the matrix. However, when I compile it, the entries appear as ...
user1234's user avatar
  • 109
1 vote
2 answers
89 views

Solve a non-trivial matrix equation for an unknown matrix

I am solving the matrix equation to pass from the Fokker-Planck to the Langevin equation. Specifically: \begin{equation} D=BB^T \end{equation} where $$ D= \left(\begin{matrix} l x_1(1-r_1) + e_1 r_1 ...
Giancarlo Creanza's user avatar
4 votes
1 answer
70 views

Commutant of set of matrices

I'm trying to compute the commutant of a set of matrices, so the set of matrices that commutes with all matrices in the original set. I'm a complete newbie with mathematica, so I would be greatful for ...
giztt's user avatar
  • 43
1 vote
1 answer
156 views

Gauss elimination with pivoting error

I am attempting to write code for Gaussian elimination with pivoting. I need my code to be able to find the maximum pivot in the column and swap the rows to ensure that the first element is always the ...
Larissa Santos's user avatar

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