Questions on the manipulation of matrices in Mathematica.

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2
votes
0answers
28 views

How to get simultaneous eigenvectors of commuting matrices? [duplicate]

So let's say there are two square matrices A and B that commute (AB-BA=0). This implies that there must exist some complete set of vectors that are eigenvectors of both A and B. Is there any way to ...
0
votes
2answers
30 views

How to get Complement function working in a For loop? [on hold]

I've been working on a piece of code that will delete small components from a nested uneven matrix (n pages, n rows, 3 columns), by deleting the pages with less than ~30 rows. However, I've notice ...
1
vote
1answer
30 views

Can I rely on the ordering of the adjacency matrix? [on hold]

Suppose I have created a Graph[{1,2..n}, {1->3, etc}], and I take the adjacency matrix of that graph. Can I rely on the fact that the i-th entry in the graph is the i-th node in the matrix? Or maybe ...
1
vote
0answers
38 views

Does a matrix need to be rationalized when calculating MatrixExp? [on hold]

I have a sparse matrix, L, and need to calculate its exponential, MatrixExp[L t], where t is ...
1
vote
1answer
98 views

Having trouble translating Matlab `fsolve` into Mathematica

I searched the site and found that someone said FindRoot is equivalent to fsolve, however, without proper options, ...
-4
votes
0answers
32 views

Creating eigenvalues of a matrix [on hold]

How do I store eigenvalues of a matrix in a For loop into a two dimensional array and then plot that array?
3
votes
3answers
151 views

Matrix with known entries but unknown size [on hold]

I am trying to perform some calculations with a matrix that has let's say size N but unknown, please How can I write this in mathematica?
0
votes
0answers
27 views

Finding the diagonal matrix of coefficients for a nonlinear set of equations [on hold]

Suppose we have $ \widetilde{k_1} $ and $\widetilde{k_2} $ in term of $k_1$ and $k_2$. We want to find a matrix that relates this variables to each other. Here is the relations. $$ \widetilde{k_1} ...
3
votes
1answer
76 views

How to tell Mathematica that my variable is a scalar

In my calculations I have these combinations PauliMatrix[1].f PauliMatrix[2] where f is a scalar function. The result is as ...
4
votes
3answers
142 views

How to produce a matrix plot from 3 matrices a, b and c following RGBColor[a[[i,j]],b[[i,j]],c[[i,j]]]?

I am trying to produce a single-plot from 3 matrices, let's say: ...
0
votes
1answer
61 views

How does one initialize large arrays in Mathematica with a structured format? [closed]

I want to create a 10 by 10 matrix that increases by 1 every unit across like: 1 2 3 4 5 6 7 8 9 10 11..... Is there a function that does this without having ...
7
votes
1answer
104 views

Challenging matrix sorting request?

I have an application in mind, and I need to do the following analysis, but am having a high degree of difficulty conceptualizing it in terms of syntax. I understand what I want, but cannot seem to ...
0
votes
0answers
41 views

Mathematica error code 0x00000171

I'm getting above error code with a Trap 132 indication when attempting an ArrayPlot of a complex 130000 x 2048 matrix. Using Mathematica 9.0.1 with Mac OS 10.10.3 ...
2
votes
1answer
71 views

Extracting a time series from a sound object

After importing a sound file, how can I generate a time series (preferably as an $n\times 1$ matrix) which gives the intensity at equal time intervals?
1
vote
1answer
78 views

Unexpected inefficiency when calculating matrix product by Dot

There is an unexpected inefficiency when I calculate matrix product by Dot. The only relevant part of my code is presented as follows: ...
0
votes
0answers
47 views

Null space of a stochastic matrix [closed]

I want to calculate NullSpace of a matrix m - IdentityMatrix[n]. Normally I would do it with ...
4
votes
2answers
78 views

Pauli matrices — simplify expressions without printing out the raw matrix

Squaring a Pauli matrix results in the identity matrix. These bits of documentation (weakly, to a Mathematica-newbie like me) imply that some algebraic identities that link the Pauli matrices ...
0
votes
0answers
32 views

Why is there a different eigenvector for the same matrix? [duplicate]

I have a matrix that depends on two variables x and y. Matrix[x,y] When I make x=-.25*(1 - 1/3) + .25*(1/3) + .25 y=0 I ...
10
votes
1answer
210 views

How do I create a triangulated surface from points?

I have a set of points in a nx3 matrix and I would like to convert them into a surface, so that I may calculate its surface area. The function ListSurfacePlot3D creates the surface how I want it. ...
3
votes
2answers
104 views

Matrix Plot: How to Apply color function to only a region of the plot

I want to make a matrix plot where a color function is applied to a region of a matrix. Those matrix elements which were not in the region specified should not have any color associated with them, and ...
1
vote
1answer
63 views

How to specify positions in a matrix by an array?

If I have an array of sets of points such as pts = {{2,4},{1,3},{5,7}} Is there any super short command to use those pairs to output their respective elements in ...
-1
votes
1answer
79 views

How do I store Eigenvalues of a 14*14 matrix in a For loop into an array and then plot that array? [closed]

I have a matrix 14*14 that is dependent on parameter a. How can I plot eigenvalues of the matrix according to varous values of a?
2
votes
5answers
183 views

Add values from a list, at positions from a list, to a matrix

I'm investigating matrix assembly and one of the things I'm trying to do is add specific values to a larger matrix based on a list which is essentially defining connectivity of nodes. For example: ...
0
votes
0answers
41 views
0
votes
0answers
43 views

Normalized, symbolic Eigenvectors without abs(), sign() etc

I'm trying to compute the normalized eigenvectors of a matrix M = {{0, 0, 0, 0}, {0, 0, M5, 0}, {0, M5, 0, M4}, {0, 0, M4, 0}} If I try Normalize ...
0
votes
0answers
44 views

vector product defined on kronecker delta [duplicate]

I have some vectors such as : a={{0}, {0}, {0}}; b={{1}, {1}, {1}}; c={{1}, {1}, {0}}; I wanted to product a by ...
2
votes
1answer
56 views

formatting matrix

I have imported a matrix from data file which was generated in Matlab. The problem is the character (") in beginning and end of every row. So I can not perform any operation on it. How to get out ...
4
votes
1answer
169 views

Eigenvalues of matrix not giving imaginary parts

This might be a very simple problem, but I can't seem to figure out why I am getting this. I am trying to find the eigenvalues of the matrix: ...
0
votes
0answers
64 views

Operatorial matrix

Suppose I have a matrix M=$\begin{pmatrix} A(p) & B(p) \\ C(p) & D(p)\end{pmatrix}$. I want to apply some operatorial matrix E such that EM=$\begin{pmatrix} 0 & \partial_p & \\ ...
3
votes
1answer
59 views

Recognising degenerate maxima in a matrix

Say I have the following matrix $\left( \begin{array}{cccccc} 1. & 0 & 0 & 0 & 0 & 0 \\ 0 & 0.707107 & 0 & 0 & 0 & 0.707107 \\ 0 & 0.707107 & 0 ...
0
votes
1answer
52 views

Designing a loop that fetches 5 random vectors each with 5 components from a set of 10 until Linear dependence is found

I am currently trying to find a way to make a loop that will select 5 random columns without replacement of a 5x10 matrix until it finds a determinant equal to 0 out of the new matrix formed by the 5 ...
0
votes
1answer
29 views

Problem with writting into a matrix in Mathematica [closed]

I have declared a matrix using S = ConstantArray[0, {246,246}] And when I try to write into it by a loop I get the following error "Tag Times in 0\ Null is ...
2
votes
1answer
75 views
-1
votes
1answer
144 views

Strange bug involving a list, “Objects of unequal length” [closed]

sortedTally is a list generated from Tally sortedTally[[1]][[1]] is a list If I print: ...
0
votes
1answer
54 views

How to count column occurrences in a matrix?

I have a matrix of data, and I want to count the number of columns that match, and have some way to organize them by frequency. But I don't want to count the entire column, but consider the matrix ...
1
vote
1answer
48 views

How to swap tensor indices without permutation?

Say I have a tensor of rank R, How to swap $i^{th}$ and $j^{th}$ tensor index? I do not want to use TensorTranspose because it requires to write down the entire permutation, i.e. ...
7
votes
2answers
304 views

Defining quantum-mechanical Bra and Ket operations

I have the following ket in the Fock basis: $\vert3, 0 ,1\rangle$, where each entry defines the number of photons in a particular mode and can take any one of the following numbers: 0, 1, 2, 3. As a ...
1
vote
1answer
140 views

Transform linear system into a matrix form

I have a system of linear equations in variables $A_n$ of form: $$ \sum _{k=-K}^K h_k A_{n-k} J_{n-k}\left(\frac{(1-i) \text{$\eta $Sqrt}(n-k)}{\sqrt{2}}\right)+A_n\left(\frac{(1-i) \eta ...
0
votes
1answer
69 views

Creating Matrix,Inverted and Upper Triangulate inside Module

I was trying to fit this into a module but I didn't have any luck. And for some reason it won't Inverse the Matrix. Here's the code: Input: ...
-1
votes
1answer
62 views

Help needed with assignment [closed]

Can I get some help with this: Write a module which as an input receives two matrices, the first matrix transforms in to the same matrix, but in the new matrix occur absolute values of the first, ...
4
votes
2answers
154 views

Improve simulation speed using Compile

I have two square matrices, a hermitian matrix h and an unitary matrix v. I am interested in the following function ...
0
votes
0answers
56 views

Which method to use for finding maximum without actually computing optimization function explicitly?

I am new to Mathematica and I am currently working on an optimization problem. The optimization function that I have easy to calculate for some assignment of variable but it is very difficult to ...
-1
votes
1answer
64 views

Module whose input is a function of 2 variables [closed]

I need to make a Module whose input is a function of 2 variables and 2 variables m,n so i can make a Matrix with Array. Basicaly, I need this: ...
1
vote
2answers
79 views

Matrix with infinity on main diagonal

The question is trivial, however, there might be unexpected solutions. What would be nice way to create a square matrix with $\infty$ on main diagonal, and some arbitrary constant everywhere else? My ...
2
votes
2answers
222 views

How to make Mathematica show matrices and vectors nicely

It shows me like {{0}, {1}, {0}, {-1}} . Is it possible to make it look like a vector, always?
5
votes
3answers
168 views

Constructing a grid from a matrix

I would like to construct a grid from a matrix. For example, one possible matrix is $M1$. $$M1= \begin{pmatrix} c2 & a1 & a1 & a1 & a1 & a1\\ a2 & b1 & c2 & a1 & ...
0
votes
1answer
74 views

Symbolic matrix calculation [closed]

I have question about a matrix calculation like $\mathbf{b}^{t}\,\Sigma\,\mathbf{b}$, where $\Sigma$ is a 7 by 7 matrix, and $\mathbf{b}$ is vector of 7 elements, and each element in the vector ...
0
votes
1answer
56 views

Symbolically solve system of equations involving matrix

I need to solve the following system of equations symbolically for a_i, b_i, and c_i: ...
1
vote
1answer
98 views

Extract coefficient matrix $A$ from expression $f(x)$

I have expression: $$f(x)=\sum_{i=0}^{K-1}\sum_{j=0}^{N-1}a_{i,j}e^{ix}x^j.$$ I want to extract coefficient matrix $A$ from expression $f(x)$ where $$A=\left( \begin{array}{ccccc} a_{0,0}& ...