Questions tagged [matrix]
Questions on the manipulation of matrices in Mathematica.
2
votes
0answers
43 views
How to calculate a projection of x,y,z data to x any y plane?
I have a List containing x,y,z data, which I can plot nicely in a ListContourPlot:
...
1
vote
1answer
60 views
How do I extract the matrix from an density matrix equation?
I have a density matrix equation and I wish to put it in the form of a matrix.
For example, if I have:
$$\rho =Ax_{1}x_{1}+Bx_{1}x_{2}+Cx_{2}x_{1}+Dx_{2}x_{2}$$
Copy-and-paste version
...
0
votes
1answer
43 views
Matrix definition using some rules for the elements
I'm gonna produce a matrix in which the matrix elements obey the following rules
$\left<n \right|M \left| m \right> = m^2 \delta_{m,n},$
$\left<m \pm 2 \right|M \left| m \right> = (1-m) ...
1
vote
1answer
54 views
Why doesn't the matrix rank decrease in this case?
Consider the square matrix $M(k)$ of dimension 6
$ M(k) = \frac{1}{\sqrt{2}}\begin{bmatrix} 0 & 0 & 1 & i & 0 & 0\\ 0 & 0 & 0 & 0 & ie^{-ik} & e^{-ik} \\ 0 &...
5
votes
4answers
379 views
Looking for a simple way to manipulate one column of a matrix
Given
{{a, b}, {c, d}}
I want to get
{{c, b}, {a, d}}
with one simple expression. Is this possible?
1
vote
2answers
80 views
Selecting matrices based on existence of unique column and row of all equal terms
So, I have a list of lists of lists such as the following:
{{{4}},
{{7, 7}, {7, 7}},
{{5, 5}, {6, 6}},
{{2, 1}, {1, 1}}}
Interpreting the elements of this list ...
0
votes
0answers
25 views
Relation between matrices
Maybe this is not a usual question for this forum...
I have the following two matrices, Ds and Dss, respectively:
...
1
vote
2answers
50 views
Matrix with simplified EngineeringForm
I have the following numerical matrix:
Ds={{0.0002773500981126146, -0.0002773500981126146},{0.0005547001962252292,
-0.0002773500981126146}}
I would like to ...
0
votes
0answers
31 views
Root (#1^3 …) How exploit the result of Matrix Eigenvalues [closed]
I try to determine the Eigenvalues of matrix[4x4] (algebraic results) but I don't understand the result.
How exploit the result with #1^3 ? I would like find a algebraic result for each eigenvalues. ...
0
votes
1answer
47 views
Strange result of MatrixFunction
Let us consider the sum of the matrix series
m = 2; n = 3; Sum[MatrixPower[{{1, 2}, {3, 4}}, m + k*n]/(m + n*k)!, {k, 0, Infinity}]
{{-(32 E^(-(5/4) - Sqrt[33]/...
1
vote
1answer
41 views
Why am I getting incorrect Eigenvectors for my matrix? [closed]
When i try and compute the Eigensystem using Mathematica i am getting negative values for my Eigenvector, but my Eigenvalues are correct but my Eigenvectors are incorrect and i do know why is that?
\...
4
votes
3answers
785 views
How to speed up large double sums in a table?
I am calculating a 3-by-3 matrix whose elements are given as follows:
$$
M_{mn} = \frac{1}{N}\sum_{i=1}^N \sum_{j=1}^N (r^i_m - r^j_m)(r^i_n - r^j_n) \tag{1}
$$
where $N$ is the total number of ...
0
votes
1answer
37 views
Simplifying an expression involving a matrix and functions of it
I have implemented the following two matrices in Mathematica in order to compute s, but I don't know how I can further simplify the resulting expressions, e.g., ...
1
vote
1answer
28 views
Verify that a PDE is satisfied by a matrix consisting of functions satisfying a different PDE
My problem is as follows: I have two matrices $P$ and $Q$ which are made up of algebraic expressions of a function $q(x,t)$ which solves a somewhat complicated pde, and its derivatives, for example, ...
0
votes
1answer
50 views
How do I create a Jacobian matrix for a large system of equations?
I would like to create a Jacobian matrix using the simplified functions below:
f1[a_,b_,c_]:= a^2 + b^2
f2[a_,b_,c_]:= c/2
f3[a_,b_,c_]:= b^3
I say simplified ...
1
vote
2answers
49 views
Matrix whose coefficients are functions
What is the right way to declare of matrix whose coefficients are functions of a variable $x$ ?
I tried :
Table[Table[a[i,j][x_],{j,1,NN}],{i,1,NN}]
3
votes
2answers
342 views
How to denote matrix elements succinctly? [closed]
Is there a more elegant way of dealing with the following subscripting?
...
1
vote
1answer
15 views
Show result of matrix operation in terms of user defined matrices
I have defined some matrices K[0],K[1],...,K[9] and S[1],...
6
votes
4answers
354 views
0
votes
1answer
35 views
How to create a dot product version of the product function
I would like to create a function to matrix multiply (dot product) n matrices together, where n is large, for example
M1*M2*M3*M4*M5*...*Mn
I know there is the 'product' function that can do this ...
0
votes
0answers
73 views
Plot the maximum of the real parts of the eigenvalues of a trancendental equation
Basically I have this matrix
...
0
votes
0answers
49 views
How to make a compiled version of a function?
I'm trying to make a compiled version of this function
...
2
votes
1answer
54 views
Efficient computation of matrices involving large sums of KroneckerDelta's
I was wondering if one could benefit from Mathematica's rich linear algebra methods for diagonalizing 2nd rank tensors. Namely, in the context of systems (fluids) comprised of capsule-like particles, ...
0
votes
1answer
24 views
Problem with solving a system of equations based on a matrix
I am trying to solve a system of equations based on a matrix in order to find the "stationary" matrix. the code I've written should break the matrix down into a system of equations such that some ...
2
votes
1answer
39 views
Matrix Decomposition and Collect
I am looking to decompose a matrix in terms of a sum of matrices with the same coefficients, i want something in this form :
$ m1=
\begin{pmatrix}
a^2 + 2a + 3 & 1 \\
2a & a^2
\end{...
4
votes
2answers
310 views
`FindRoot [ ]`::jsing: Encountered a singular Jacobian at a point…WHY
I have a large system of linear and nonlinear equations. I know that the system is not singular at the point given because I calculated the Jacobian and evaluated it at a given point. The resulting ...
0
votes
0answers
40 views
Why is this iterative process with matrix calculation so slow?
I am trying something similar to the following code with Ntime as large as 100 or so. Now it's very slow as shown by the Ntime=3 ...
0
votes
2answers
50 views
Apply matrixform to limited rows and columns of a matrix
I have a big matrix, you can say 1000*1000 whose elements are functions of several parameters such as a, b. I wish to see just a ...
3
votes
1answer
59 views
What's the easiest way to combine specific columns of two matrices?
given matrices
A = {{3, 10, 10, 5.`}, {4, 10, 10, 6.`}, {5, 10, 10, 7.`}}
B = {{6, 10, 10, 5.`}, {7, 10, 10, 6.`}, {8, 10, 10, 7.`}}
how can i get a matrix which ...
0
votes
1answer
88 views
An example of symmetric, real entry matrix with non-real eigenvalues, according to Mathematica. Is this a bug?
The following matrix is symmetric and all entries are real,
...
1
vote
1answer
46 views
Matrics manipulations
this is a basic question in Mathematica, I hope to get help to resolve it,
How I can extract elements from matrics for example
I have
...
0
votes
2answers
68 views
Function for finding the nth unique minimum value in a list?
I have this matrix...
mat = Table[{k, 0}, {k, 0, limit}];
After a series of dynamic iterative operations, some of the 0 initialized entries (i.e., those of the ...
1
vote
2answers
42 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).
<...
0
votes
1answer
91 views
How to construct — based on physics-type notation — a magical simplex $\mathcal{W}$ of bipartite qutrits?
I have a short Mathematica program:
...
1
vote
1answer
30 views
Defining a function that outputs a matrix, and later finding its eigenvalues
I am trying to do the following:
I have a simple 2x2 matrix that depends on three parameters (physically -- momentum coordinates kx, ky, kz). Then I want to replace each of these parameters by a ...
0
votes
1answer
67 views
Vector and matrix multiplication
I have a question: Given a vector $v=(1,0)$ and a matrix $A(φ)= \begin{pmatrix}
cos(φ)&-sin(φ)\\
...
1
vote
0answers
44 views
Confusion matrix using data from two matrices
I have a problem. Any help will be appreciated.
In order to calculate the accuracy, sensitivity, sensibility and F1 score between diseases and their symptoms, I have two matrices with a different ...
0
votes
1answer
114 views
Wrong calculation with matrix exponential (MatrixExp)
I've been doing some calcultations on mathematica which involve exponential of matrices. It's well known that if [A,B]=0 then [A,F(B)]=0 where A,B are matrices and [,] is their commutator. Nonetheless,...
3
votes
2answers
88 views
Efficiently find all values of parameter such that any of the eigenvalues of a matrix is equal to 1
I wish to find all values for a parameter such that my matrix has an eigenvalue of 1.
Here is an example 16-by-16 matrix with elements depending on the parameter x ...
2
votes
2answers
96 views
How can one do looping with matrices for large N (= 100, 200, etc), where N is the matrix size of a given form, to get N eigenvalues?
I want to generalize the following to large N:
...
2
votes
2answers
77 views
Using good method to produce a regular matrix
The matrixform is as follow, and how can I use good method to produce it?
H = {{1, 1, 0}, {2, 2, 0}, {0, 1, 1},
{0, 2, 2}, {1, 0, 1}, {2, 0, 2}}
1
vote
1answer
56 views
Least squares fit of a symmetric linear system
I have $q$ measurements with $p$ different excitations.
In one special case, they might be equal in length. For example, I might have 12 measurements ($q=12$) with three excitations each ($p = 3$), ...
2
votes
1answer
28 views
Maximally expand tensor series?
I am trying to obtain a power series expansion in some real parameter, but all the terms are arbitrary products of tensors. I.e. I want to expand an expression containing sums/products/powers of this ...
0
votes
0answers
44 views
How can I speed up my code finding the parameter which yields zero determinant for increasingly larger matrices?
I build a square matrix with matrix elements dependent on the parameter x. I need to find all values of x within a reasonable ...
1
vote
1answer
21 views
How to define a function, that generates matrix of variables, which can be later used in Reduce?
My goal is to generate matrices, on which I will put different constraints in Reduce funcion, e.g.:
...
3
votes
1answer
110 views
Identify maximum difference in Matrix
i am trying to find the Maximum difference between two matrices and identify where this maximum occurs.
I illustrate what I mean using an example.
Given
...
4
votes
1answer
43 views
Strange bug in LUP Decomposition
I have written LU decomposition with partial pivot, but for some matrices, the entry L[[1,1]] isn't equal to 1 like it should be,...
1
vote
0answers
46 views
Noise covariance matrix
I am trying to find the noise covariance matrix of a random vector $\mathbf{x}$ with itself. The elements of this vector represent image pixels and are treated as random variables i.e, $\mathbf{x}=\{...
0
votes
1answer
54 views
How to replace the entries of a matrix by another matrix?
I have a two matrix mm and nn. Matrix mm is of dimension 8 cross 8 and nn is of dimensions 4 cross 4. I want to replace the first four rows and columns in mm by nn. How to do this?
...
0
votes
0answers
32 views
Dynamical PlotLegends with two indices
I need to plot several eigenvalues from different matrices, so I would like to know how can I change the name of the curve with each set of matrices-eigenvalue. What I am doing is the following:
<...
