Questions on the manipulation of matrices in Mathematica.

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4
votes
1answer
62 views

Creating a tensor from matrices

I have 3 nxn matrices that I'd like to combine into a nxnx3 tensor. Basically, I want a new nxn matrix where each element is a 3 tuple of the elements of the other 3 matrices at that same position. ...
3
votes
2answers
104 views

Matrix Diagonalization programming

I have a very simple problem, with me misunderstanding the use of Modules and Functions in general, in mathematica. I have a function of which I want to input a Matrix, and in the function I want ...
3
votes
2answers
133 views

Summing matrix products

I need to compute a double sum over a weighted matrix product: $L[M]=\sum_{i,j}^{N}\Lambda[[i]]\;\omega[[i]].M.\omega^{\dagger}[[j]]$. $\Lambda$ is a list of with N complex values(weights) and ...
0
votes
0answers
78 views

How to Extract and Rearrange Elements in Doubly-Nested Lists

Hopefully any easy problem for you guys to help me with! I'm currently having an issue with writing some Mathematica code that will extract the each nth element in each array within a matrix, and then ...
6
votes
1answer
452 views

What does it mean when Mathematica returns a zero “eigenvector”? [closed]

For example, I ask Mathematica to compute the eigenvectors of $\left(\begin{array}{cccc} 1 & 1 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 5 & -4 \\ 0 & 0 & 4 & ...
1
vote
3answers
78 views

Percent Difference between elements from 2 matrices

If i have a 22 by 25 table of values which depend on n and r, and a list of values that depends on r that is a 22 by 1 matrix, how can I find the percent difference between each element, by row in the ...
0
votes
2answers
53 views

Plotting plane from a matrix or data table

After weeks collecting data I've decided to pass my results through Wolfram Alpha and see what it gets. The results are amazingly useful, specially the plane generated by linear regression. It is ...
3
votes
2answers
145 views

Zigzag ordered encoding of DCT co-efficients

I am doing DCT steganography. I have obtained a matrix of DCT co-efficient. I now want to perform zig-zag ordered encoding. The matrix is as follows ...
3
votes
0answers
75 views

How to force Series[] to compute expansions by considering non commutative multiplication?

I wish to compute the Taylor series expansion of the following iteration method $x_{k+1}=x_k-f'(x_k)^{-1}f(x_k)$ up to four terms of error ($e_k=x_k-\alpha$). When this is a scalar iteration, I very ...
0
votes
1answer
42 views

Plotting results of 'Do' loop in contour graph

I want to plot the results of a 'do' loop as a contour graph: ...
3
votes
1answer
152 views

How can I optimize the search between two lists, one that is changing length?

I'm trying to identify unique arrays by comparing two lists, one which is growing in length. The number of elements in the list grows as 2^n^2, where ...
6
votes
1answer
118 views

Issue in Det[…] when computing determinants of polynomials?

When I form a matrix of at least size $12 \times 12$ of second order polynomials in $w$ and I calculate the determinant of that, I get something that is a rational expression in $w$. Since the ...
1
vote
2answers
85 views

Plot values of an $m\times n$ matrix on the complex plane with color varying along $m$

Let's say I have a complex valued matrix $\begin{pmatrix}1+I&2+2I&3+3I\\4+4I&5+5I&6+6I\end{pmatrix}$ represented by a list: ...
4
votes
1answer
57 views

How to create overlapped block matrices and simplify the result

This is sort of a duplicate of Creating overlapped block matrices, but the question wasn't fully answered since the OP never returned to clarify. I am using Kuba's answer for FEM, but I have been ...
0
votes
1answer
55 views

Make Function from matrix [closed]

I have a set of excel data (time v temperature). When I extract it to mathematica it creates a matrix. I want to put the temperatures into a function that is time dependent, so is there a way to use ...
0
votes
1answer
119 views

Solving linear system with constraints

I need to come up with a solution for a rather, odd situation. Let's say I have an $M \times N$ matrix called ${\bf A}$, and I would like to solve it for ${\bf x}$ where $b_1 \le {\bf A} {\bf x} \le ...
1
vote
3answers
68 views

How to convert a matrix into a sparse matrix [duplicate]

If I have a matrix: row 1)1 0 0 4 row 2)0 0 0 0 row 3)5 1 0 0 row 4)0 5 0 0 row 5)0 0 0 9 How would I put it in a sparse matrix format: ...
7
votes
1answer
86 views

A few tuples at a time?

I want to generate $n$ by $n$ binary arrays, and then reduce the output from those arrays by performing a number of permutations and eliminating duplicates. The problem is that the number of arrays ...
5
votes
2answers
240 views

Speed-up the computation of this sum of small matrices

Given a matrix mat with a large number of rows (a few thousands) and a few columns (between 2 and 10), I'd like to compute the sum of the "small" matrices obtained ...
0
votes
0answers
39 views

Problem with stress transformation using InputField

I want to write a code for application of the transformation matrix onto a second-order stress tensor. I have a problem with showing the results. My steps are as follows: 1) I create a Grid with ...
-3
votes
1answer
46 views

Singular matrices with index 1 [closed]

If $A\in \mathbb{R}^{n\times n}$, the index of $A$ is the smallest integer $k$ such that $rank(A^{k+1})==rank(A^k)$ I want to find a singular (id est $\det(A) == 0$) and non symmetric matrix $A$ ...
1
vote
2answers
52 views

Importing data, then plotting ListPlot. What's the most efficient way to write a code?

It should be a boring question to ask for someone, but this is very basic need which I haven't resolved by myself. I know I can use MapThread and pure function to make it short and beautiful, but even ...
14
votes
6answers
405 views

Given a large binary matrix, find the largest submatrix containing non-zero elements

I'm looking for a way to reduce a binary matrix containing zeros at some positions into a matrix that contains no zeros by deleting rows and columns of the original matrix until only non-zero values ...
1
vote
1answer
37 views
9
votes
4answers
243 views

How to convert a sparse matrix to a list of sparse arrays?

I have a matrix stored as a SparseArray. How can I convert it to a List of its rows, where each row is stored as a ...
1
vote
2answers
72 views

Is it possible to draw a line on a MatrixPlot that would reflect density of row values? [closed]

I have a MatrixPlot with some data and I'd like to draw a vertical lines representing the "average" (density) of that data for each row. Something like this for ...
5
votes
3answers
118 views

Finding most general matrices $A$ and $B$ such that $A\cdot B=1$

I would like to find the most general shape of matrices $A$ and $B$ such that $A\cdot B=1_{4\times4}$. Naively, I just define for example ...
0
votes
1answer
60 views

Varying constant in Matrix calculation to generate 3D plot

As suggested, I rewrite my code to make it simpler and directly showing the problem. Here is a short example. I'd like to generate 3D plot where x,y,z (= a,b,answer) while I am varying a (0 ...
-1
votes
1answer
67 views

Find inverse of the parametric matrix [closed]

I want to calculate the bellow parametric matric but I faced with this error: any suggestion?? ...
4
votes
4answers
274 views

Constructing a large tridiagonal matrix with alternating signs

What is the best way to construct a large tridiagonal matrix, in the following form (notably with alternating signs)? $\mathbf M = \begin{pmatrix} 0 & a & 0 & 0 & 0 & \cdots ...
3
votes
0answers
77 views

Find the generators and group description of a set of matrices [closed]

I have the following matrix elements: ...
2
votes
2answers
118 views

Repeated multiplication of a square matrix and a column vector in Mathematica

I am very new to Mathematica and StackExchange, so pardon me if I am repeating a question that has already been answered. I am trying to use Mathematica to do the following: u[n+1] = A.u[n] where A is ...
11
votes
2answers
376 views

Expressing the n-th power of a matrix [duplicate]

My matrix is $\qquad A= \begin{pmatrix} {1} & {2} & {3}\\ {4} & {1} & {0}\\ {0} & {5} & {4} \end{pmatrix} $ I need $\qquad A^n$ I tried ...
6
votes
6answers
249 views

How do I build a patterned matrix (high-pass and/or low-pass filter bank)?

I would like the shortest code to build the following matrices, of arbitrary dimension $N$: A Low-Pass filter bank matrix is of the form $ \begin{bmatrix} 1 & 1 & 0 & ...
3
votes
0answers
147 views

Mathematica's Singular Value Decomposition different from another math engine [closed]

I’ve been working with SVD – singular value decomposition. Things weren’t working as expected. Thus, I looked over to Matlab and executed the following code: ...
3
votes
2answers
390 views

How do I get the inverse of a homogeneous transformation matrix?

I want to get the inverse of this homogeneous transformation matrix: iab = { {1, 0, 0, 0}, {0, 0, -1, 0}, {0, 1, 0, 3}, {0, 0, 0, 1} } ...
9
votes
1answer
101 views

UnitaryMatrixQ function not returning true for a unitary matrix

So I know this matrix is unitary. It's a well proven fact in quantum mechanics and you can even check for yourself on pen and paper, Heres a quick proof: Assume $H$ is hermitian (i.e. $H^\dagger=H$) ...
1
vote
1answer
44 views

Array Flattening arrays of matrices given by rules

Fix an $n$ and an $m$ positive integers.I have some set of four $n\times n$ matrices $A$,$B$,$Y$,$Z$ (where $Z$ is the zero matrix). I'd like to input the $nm\times nm$ matrix of block matrices given ...
1
vote
2answers
113 views

Update: Calculate Tensor products and traces with Mathematica

My goal is to algebraically simplify expressions involving tensor products and taking the trace. That is, I would like to compute $\operatorname{Tr}\left( \prod_i(id+a_i \otimes b_i) \right)$, using ...
12
votes
7answers
628 views

Brackets around each item in matrix

I have a matrix where every item in the matrix has its own brackets that I do not want. How can I remove the brackets around each item?
1
vote
0answers
29 views

MatrixForm in Mathematica [duplicate]

I wanted to do subtractions between to matrices and I did the following ...
0
votes
1answer
71 views

what do those signs #1, #1^2, #1^3, & mean here? [duplicate]

I have read common pitfalls page and the documentation page but I still don't understand what do those signs mean here? ...
-7
votes
2answers
65 views

How to solve for the eigenvalue in matrix? [closed]

For which value of $a$ in the matrix {{a,2}, {3,4}} has the matrix eigenvalue of $0$? How to solve it in Mathematica?
3
votes
1answer
77 views

Calculating products of given length of two matrices

I have the following problem to solve. Let us have two given square matrices $A$ and $B$ of the same size and a positive integer $n$. I would like to produce all products of length at most $n$ of ...
7
votes
1answer
171 views

Incorrect Left and Right Eigenvectors in Mathematica

I'm trying to find the Left and Right Eigenvectors of a pretty straightforward matrix, but Mathematica doesn't seem to be able to do it for even a 200 dimensional matrix. Background: Given an ...
4
votes
0answers
164 views

Finding eigenvalues in Mathematica: why so slow?

I am trying to find the eigensystem of a large sparse real symmetric matrix, and I only need the lowest 40 or so eigenstates. The relevant code is as follows: ...
0
votes
4answers
115 views

Constructing an arbitrary dimensional matrix with a certain rule

I want to construct the following matrix $M$ of dimension $(N+1)\times(N+1)$ with the following rule (for arbitrary N). Below, in the subscript, as usual, the 1st index gives the row and the second ...
2
votes
1answer
34 views

Encoding/Decoding matrices as integers, integers as matrices [closed]

I want to convert large binary matrices of m x n dimensions into integers, and then to convert these integers to the original matrices. I attempted the following: ...
1
vote
1answer
64 views

Monitoring a matrix with changeable elements as Manipulate in plotting [closed]

If we remember, Mathematica has an ability to show a Psudo-window of plots for monitoring the effects of some changeable parameters in the functions. For example ...
1
vote
1answer
95 views

diagonalization function

If we have a matrix m which is n*n, how can I do mm=U^dagger m U which is a transformation ...