Questions tagged [matrix]
Questions on the manipulation of matrices in Mathematica.
2,446
questions
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votes
1answer
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why does mathematica not return the result of the multiplication of a symbolic matrix and a symbolic vector?
I am really stuck at a simple problem. Maybe, it is not totally a problem. However, I don't understand why.
I am trying to take the dot product of two expressions.
Here is the code:
...
3
votes
3answers
72 views
Need help with finding a matrix
Could anyone please help me find a 4 by 4 matrix A such that A.Transpose[A] exactly equals the following matrix:
...
1
vote
1answer
22 views
syntax error when defining a list of matrices: “…cannot be followed by..”
I am literally just defining a list of matrices, but seem to run into the following error when adding the last matrix. (so to be clear, I get no error when I take out the last matrix entry). What's ...
2
votes
0answers
26 views
Computing matrix eigenvalues with units
I apologize if this is a basic question or if I am not giving enough detail. I'm trying to solve for the eigenvalues of a matrix with matrix elements that have units.
...
3
votes
1answer
40 views
Using the elements of one Matrix to form a new Matrix with specified rules
Given a matrix [a], how to get matrices [b] and [c] based on the following two rules?
rule [a]->[b]: Strike out corresponding term in [a] and take product
of the remaining two terms in the same ...
1
vote
2answers
91 views
Finding the square root of a 7*7 matrix with real entries
Suppose that I have the following symbolic 7*7 matrix
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2
votes
2answers
52 views
How to reorganize matrix according to location requirements
I want to specify a location replacement for matrix reorganization. For example, when I specify the location replacement rule to be {1, 2, 3, 4} -> {2, 3, 0, 0} ...
asked Apr 1 at 10:38
Please Correct GrammarMistakes
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0
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0answers
19 views
Using NCAlgebra for Matrix Calculus
I have the following expression:
$$
F = \| \mathbf{1} \text{diag}(G)^\top P S+(\mathbf{1} \text{diag}(G)^\top P S)^\top - 2 S^\top P^\top G P S - D \|_F^2
$$
where $S\in \mathbb{R}^{M\times N}$, $P\in ...
3
votes
1answer
29 views
How do I get specific subgraphs from my adjacency graph/matrix under certain conditions?
I have the following set of code which creates a random symmetric matrix (elements 0 and 1) and a labeled adjacency graph. A 0 corresponds to no edge and a 1 corresponds to an edge.
...
1
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0answers
26 views
settings elements of matrix of functions
I have a work flow that involves initially specifying a matrix function (or a matrix of functions), e.g.
f[x_]:={{Exp[x],Sin[x]},{Cos[x],Log[x]}}
This works well ...
6
votes
2answers
151 views
How do I combine multiple matrices into a single adjacency graph?
I'm sort of new to Mathematica and have been working on a project that involves simulating newtwork changes in the form of matrices. I have the following lines of code:
...
0
votes
1answer
26 views
Grouping complicated polynom with respect to vectors/matrix
i recently wrote a code which computes the trace of a general 2-qubit density matrix to the fourth power (i´m studying physics :D), in terms of two bloch vectors and a matrix of the correlations. Here ...
1
vote
1answer
48 views
Trace of density matrix
Hi friends of Mathematica, i´m a physics student and try to calculate Tr[rho^4] for a general two qubit system analytically. Since this is a very long calculation, ...
1
vote
0answers
24 views
Sign of a determinant based on sign conditions
New user here.
I want to sign a determinant, using known qualitative conditions on the components. any help appreciated. dummy example below. thanks.
...
4
votes
2answers
142 views
Replacing parts of a Matrix with lists
I want to use lists to easily replace parts of a matrix. As an example, I want to replace the code
...
1
vote
0answers
47 views
What is the symbol for Matrix inverse operator? [closed]
I tried to take inverse of a matrix A using Inverse[A] and it gave me the right result. But when I tried using notation form A-1 by using typesetting superscript, it gives me wrong result (element ...
6
votes
1answer
54 views
Force two distance matrices to use and show a common legend
I have two distance matrices. Both are comparing two entities in the same way. I create each matrix using
...
0
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0answers
35 views
Root expressions inside Eigenvalues [duplicate]
I need the eigenvalues of this matrix as a function of Ny. When I tried whith a simpler matrix (4 x 4), it worked, but now, with this 25 x 25 matrix it returns what is shown in picture bellow:
The ...
0
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0answers
28 views
Redefine a function on certain values
This question is related to Zero-dimensional matrices, in particular to the answer https://mathematica.stackexchange.com/a/39543/42722.
In Mathematica $0 \times n$-matrices are not well-defined, so I ...
5
votes
4answers
96 views
Grouping and repeating the grouped rows inside a matrix
I'm interested in finding the quickest way of grouping the rows of a large matrix in sub-groups based on the position of non-zero elements in the first column and then repeating them number of times ...
3
votes
1answer
37 views
Create block matrix with secondary diagonals using Band function
Given matrices m1, ... , mk and matrices n1, ... , nk-1, I would like to define a block matrix
$$ m=\left( \begin{array}{rrrr}m1 ...
5
votes
1answer
116 views
Eigensystem of arbitrary 4x4 Matrix
While doing a computation, I needed to take numerical derivatives of eigenvectors of a 4x4 hermitian matrix with respect to a parameter. I ran into the issue of phase jumps -- a random phase ...
5
votes
2answers
104 views
How to get all the elements in the opposite diagonal of an element
I want to specify an element in a matrix and get all the elements in the diagonal of the element.
For example:
$$\left(
\begin{array}{cccc}
1 & 2 & 3 & 4 \\
5 & 6 & 7 & 8 \\
...
6
votes
3answers
115 views
How to randomly generate a positive semidefinite matrix?
How would I randomly generate a positive semidefinite matrix? I'm aware how to generate a random $n\times n$ matrix with real values between -1 and 1 with
...
0
votes
2answers
32 views
create a rank 1 matrix from two vectors
I've seen the answers 1 and 2 about the transposition and creation of rank $m$ matrices.
What I'd like to do is first create a random vector, which I know how to do with
...
3
votes
1answer
52 views
Matrix rank of triangular integer matrix powers. Can it be speed up?
I need to determine ranks of the powers of a triangular $0$-diagonal integer matrix of a high dimension. Doing this I noted that the time Mathematica needs to ...
6
votes
3answers
341 views
How do I modify a symmetric matrix while maintaining symmetry?
I'm trying to figure out how to create a For loop for a symmetric matrix. I have a 5 $ \times $ 5 symmetric matrix consisting of 1's and 0's and I'm trying to ...
1
vote
0answers
46 views
Determinant of the tensor matrix in Mathematica? [closed]
I have a data:
As an example, it looks like this:
Then, when I try to take Det[]:
How we can find determinant value of these kind of matrices ?
7
votes
1answer
126 views
Fastest way of numerically creating a list of dot products
I have a list of numerical complex 2x2 matrices
list = {M[4,3],T[3],M[3,2],T[2],M[2,1],T[1]}
(in reality this list contains over 1000 matrices and I have to do ...
3
votes
1answer
144 views
Having trouble solving a complicated system of equations
I've been trying to solve a system of three equations using the 4th as a parameter, but it hasn't been working. Mathematica just seems to run indefinitely even if I set a given value for the parameter....
1
vote
1answer
31 views
Using MinimumBandwidthOrdering to restructure a correlation matrix
I am trying to restructure a correlation matrix such that the variables with the strongest correlations are grouped together
Needs["GraphUtilities`"]
These are ...
4
votes
1answer
73 views
Performing Hessenberg decomposition on a symbolic matrix
I am trying to calculate the Hessenberg decomposition of a symbolic matrix
$$
A=
\begin{pmatrix}
0 & -\mathrm ia & 0 & b \cos x \\
\mathrm ia & 0 & \mathrm ic \sin x & 0 \\
0 &...
0
votes
0answers
13 views
Iterative algorithm for solving liner system [migrated]
So according to my lecture notes :
to solve Ax = b one writes A as :
$(L+D+U)x = b $
$Dx = b - Lx - Ux $
And then :
$ Dx^{(k+1)} = b - Lx^{(k)} -Ux^{(k)} $
This is the Jacobi algorithm using ...
2
votes
1answer
37 views
Manipulation of LeviCivita symbol
I have a matrix in element form as:
$$A_{ij}= \sum_{m,n=1}^3\epsilon_{jmn} B_{im} C_{jn}$$ where $B$ & $C$ are also $3\times 3$ matrices. How should I use Levi-Civita symbol in Mathematica so that ...
3
votes
1answer
54 views
Generating vectors with small inner products in a large vector space
I want to generate a large number $k$ of vectors of norm 1 in a $d$ dimensional vector space such that $k>d$. I want these vectors to have inner products as small as possible.
A crude way is to ...
1
vote
1answer
66 views
1
vote
0answers
34 views
Finding a matrix solution directly with Mathematica
I have two matrices say
M={{a,b,c},{b,d,f},{c,f,e}}
and
G={{A,0,B},{0,B,A},{A,B,B}}
Now I have done
...
1
vote
1answer
51 views
How to set same Variables with different Values [closed]
I have a pipe with different insulation sections and a fluid flowing through. I need to calculate the fluid Temperature at the end of every section, to estimate the temperature for the next section. I ...
1
vote
3answers
63 views
How can I evaluate a matrix for a set of values?
I'm trying to evaluate a system, that depends on two variables, in a specific set of values. I will write an example, but my system is more complicated.
...
1
vote
0answers
70 views
Plotting the surface spectral function
I'm not 100% sure if I should be posting this in the physics stack exchange but, I am pretty new to Mathematica, just installed it five weeks ago, and I am having a little trouble implementing the ...
1
vote
0answers
76 views
Help speeding up matrix exponent of $ 16 \times 16 $ symbolic matrix
I am trying to run the following script which involves the MatrixExp of t times a 16x16 matrix with one variable, ...
2
votes
0answers
21 views
`MatrixFunction` is returning a cryptic error message about “the function `1`”
The "Possible Issues" section of the documentation for MatrixFunction lists several possible ways in which a call to ...
2
votes
3answers
51 views
Find minimum with matrix positive-definiteness constraint
Say I wish to find the minimum value of the determinant of a symmetric matrix under the condition that the matrix be positive definite. So I attempt:
...
1
vote
0answers
28 views
Errors in NDSolve for complex matrices
This is the problem. It is quite simple, and looks unwieldy only because I had to rewrite quaternions as complex matrices.
...
1
vote
0answers
45 views
$ x $ and $ y $ coordinates in ListLinePlot [closed]
I'm trying to make a ListLinePlot with my randomly generated data, and I want one vector to be the x coordinates of the graph, ...
5
votes
2answers
83 views
Apply Outer to list of matrices and vectors
I have a list, M, of square $ n \times n $ matrices, {M1, M2, M3, ...}, and a list, V, of $ ...
4
votes
2answers
187 views
Create a matrix from the rows of another, and calculate the rank of the new matrix
This may be a very basic question, so apologies in advance, I'm a first-time Mathematica & StackExchange user!
I have a 7x3 matrix X with all rows being unique in a 2D-list format.
For example:...
1
vote
0answers
65 views
How to use MatrixPlot as a DensityPlot?
I have a 1000x1000 matrix the MatrixPlot of which gives this graph:
The code is
...
1
vote
1answer
85 views
Cryptic NDSolve::nlnum when working with matrices
This problem was initially formulated in quaternions, but I had to rewrite them to complex matrices (as they seem to be supported better). Possibly introducing some errors along the way. So the ...
3
votes
1answer
85 views
Diagonalizing a symbolic matrix
I am trying to diagonalize the following matrix
\begin{equation}
\left(\begin{array}{cccc}
{ \frac{1-K\left(x_{2}^{2}+x_{3}^{2}\right)}{1-K|x|^{2}}} & { \frac{K x_{1} x_{2}}{1-K |x|^{2} }} & { ...
