Questions on the manipulation of matrices in Mathematica.

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1answer
143 views

Why can't Mathematica compute the null space of these matrices?

I'm writing a library of functions to work with musical pitch-class vectors. One of my functions gives me a skew-symmetric matrix modulo 12 that corresponds to the differences between components of ...
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3answers
181 views

Calculating eigenvalues of a large matrix takes a long time

I have a tridiagonal matrix (1000×1000) with each element equal to $1$ except {n, n} = 2. It takes 8 hours to give me the eigenvalues?!! Here is the code I used: ...
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2answers
176 views

Manipulating elements of a matrix, to loop or not ?

I have a grid of values generated from a MATLAB evaluation. Most of these elements are 0, some 0.5 and the remainder 1. I'd like to write a mathematica script which reads in the CSV and then, in every ...
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2answers
78 views

Matrix operation (simplify)

I had a $6\times 6$ matrix ...
2
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1answer
104 views

Stochastic Predator-Prey model using Gillespie's SSA

I'm trying to model the predator-prey situation using SSA. I am very new to Mathematica so my handling of matrices is probably terrible, and that's probably adding to my confusion: ...
1
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1answer
68 views

Assigning some results after a solve procedure to the coefficients of a matrix

I have a matrix M[3,3]. After a solve procedure, I obtained these results. {{M[1, 2] -> Cos[ψ[t]], M[1, 3] -> 0, M[2, 3] -> 0, Cos[θ[t]] -> M[3, 1], M[3, 2] -> 0, M[3, 3] -> 1, M[2, 1] -> ...
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0answers
81 views

Calculating the rank of an abstract matrix

I'm trying to compute the rank of a 4x4 matrix with 4 parameters and 2 variables. I tried to calculate its rank under some assumptions on those conditions and I kept getting rank 4. So I did an ...
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2answers
82 views

Nonlinear matrix equation solving in Mathematica

is it possible to solve below equation in Mathematica? A.X+B.Exp[X]==C A, B are square ...
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0answers
71 views

Calculate the matrix M such M.X=omega

I would like to determine the matrix M[3,3] such as M.X=w. ...
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0answers
343 views

How to invert a matrix with 100 trillion elements?

I have a $10^{7}\times 10^{7}$ matrix with the following properties: it is sparse it is gamma-5 it is almost Hermitian. If $M$ is the matrix we are trying to invert, we know $M=A M^{\dagger} A$ ...
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3answers
266 views

How to build a matrix from a set of vectors and other matrices using ArrayFlatten

I want to build a 6 by 3 matrix, from the following: one vector is 3 by 1, then a matrix, which is 3 by 2. These will go to the top 3 rows. Now the bottom 3 rows, I'll have 3 vectors each is 3 by 1. ...
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2answers
110 views

Solving matrix equation

How can I solve the forward equation S[t]=C+A*S[t+1]*(Inverse((I-B*S(t+1)))*A for t=1 to t=10 and ...
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0answers
74 views

Find algorithm or generator formula with automated procedure and pattern recognition

I am trying to find a generator formula for the discriminant of a polynomial and believe it would be an interesting problem for the Mathematica community to know how to automate evaluation of certain ...
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2answers
184 views

Diagonal minors of matrix

I need to calculate the minor of a matrix. I am going to use Mathematica example here, ...
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3answers
159 views

List manipulation: Dropping first or last row or column of a matrix

How do I drop the first/last row or first/last column from a matrix? The general case is answered here but I am new to Mathematica and it the arbitrary case is unnecessarily complex. Suppose I am ...
0
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1answer
73 views

Elements inside arrays seem to be strings rather than signed numbers

When I have code like b = Array[Subscript[be, #] &, {3, 1}] b = b /. {Subscript[be, k_] :> Subscript[-be, k] /; k > 1} I am noticing that Mathematica ...
4
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3answers
182 views

Replace elements in matrix to make it symmetric using automated procedure

I am generating a matrix using (mat2 = Array[Subscript[a, ##] &, {4, 4}]) // MatrixForm but would like to force Mathematica to make it symmetric. Thereby I ...
2
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1answer
120 views

Force Mathematica to return numerical answer to (relatively) complicated differential function

I am trying to take the Laplacian of the LogDet of a 2x2 matrix that I call V\[ConjugateTranspose].V, and actually get a number out at the end. Why does Mathematica ...
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1answer
76 views

How to plot first and second row from matrix to a graph

i have this function: ...
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0answers
21 views

Manipulating nested matrices columnwise [duplicate]

I have a project that requires analyzing large volumes of excel sheets at the same time. I have been having trouble figuring out how to index the imported files and manipulating them. The way I am ...
0
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1answer
82 views

How to obtain a convergent solution iteratively for a linear system of equations

I am working on a problem that requires an iterative procedure to solve a linear system of equations, the system of equations in matrix form is: $$\underbrace{\begin{bmatrix} r_{11} & r_{12} ...
0
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1answer
46 views

Why Table is not giving me the same sequence for eigenvalues of matrix

Let consider a matrix and evaluate the time dependent eigenvalues M[t_]:={{Sin[t],Cos[t]},{t,t*t}}; e1[t_]:= Eigenvalues[M[t]] Now If I evaluate ...
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0answers
82 views

How to find Pauli matrices

I wanted to find the Pauli matrices, so i wrote down this code: z = {{a, b}, {c, d}} i = {{1, 0}, {0, 1}} Solve[z.z == i, {a, b, c, d}] and mathematica gave me ...
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1answer
59 views

Reduce Vector/Matrix mod N [closed]

If I have a vector such as below and want to reduce it mod a number, how can I do this? V = {{176}, {648}}; MatrixForm[V] MatrixForm[V, Modulus -> 26] Both ...
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0answers
223 views

Solving Symbolically Equations with Vectors and Matrices

I want to solve equations with vector variables and vector/matrix parameters symbolically. As a basic example I would like to be able to solve something like $[I-aG]x=b$ where $a,b \in \mathbb{R}^l$ ...
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0answers
98 views

Replace part of a matrix

I have to generate a ne numbers of matrices with 1 and 0 and then replace some elements. ...
5
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4answers
517 views

Elegant mehod of generating this matrix?

Good evening, I need to determine an elegant (as possible) method of computing an nxn matrix below (the matrix shown is just a 16x16 example). I've been toying with For loops, Tables, Bands, ...
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1answer
322 views

Code efficiency improvement needed solving problem 499 in Project Euler

I am trying to solve https://projecteuler.net/problem=499 by constructing a transition matrix and finding its steady state. Here is my code: ...
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1answer
78 views

How to paste matrix to website and Email?

I tried to copy matrix from Mathematica to website, only end up with lots of garabge like this: ...
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2answers
62 views

How to edit a list according to the other list? [duplicate]

Gday guys. This problem troubles me, and I hope you can help me solve it. Say I have two random lists L1={{2},{5},{1},{0},{4},{7},{8}} L2={2,5,1,0,4,7,8} and ...
4
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2answers
176 views

How to check whether elements of a list meet a condition without generating the whole list first?

I have to find the number of elements satisfying a given condition from the set: Tuples[Tuples[Tuples[{0,1},n],n],m] The condition for $n=3,m=3$ is: ...
8
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3answers
699 views

The magic square function

There're some matrices that the sum of columns, sum of rows, and sum of diagonals are the same value. Here is an example: ...
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0answers
42 views

Failure to evaluate functions of derivatives of Theta functions

I define a variant of the EllipticTheta function (multiplied by a constant factor) : ...
0
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0answers
110 views

Solving a system of equations involving partial derivatives for a wave

Before saying anything about the problem, I have checked "How to solve a system of partial differential equations?" yet it does not actually answers my question, as I have a 10x10 matrix to work on. ...
5
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3answers
611 views

Get Eigensystem to return orthogonal eigenvectors for Hermitian matrix

I have a Hermitian matrix, and I would like to get a list of orthogonal eigenvectors and corresponding eigenvalues. But when there are degenerate eigenvalues, sometimes Eigensystem/Eigenvectors ...
8
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7answers
302 views

Input a square matrix and return a list of the matrix entries read by antidiagonals

I have a square matrix: {{1,2,3},{4,5,6},{7,8,9}} and I want to get a list: {1,2,4,3,5,7}
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3answers
76 views

Form a matrix to have inequality elements

It looks like a silly question, but I could not find any answers online. Your help is greatly appreciated! Say I have two lists now. ...
0
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0answers
56 views

Does Mathematica support Laguerre Polynomials of Matrix Argument?

I am wondering whether Mathematica can also compute the Laguerre polynomials of matrix argument as the appear in multivariate statistics? For example, they appear in this paper here: ...
1
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1answer
83 views

Wrong generalized eigenvalues of large numeric matrices

I've been working on a toy model of a variational method of a Hamiltonian H with an overlap matrix S. The point is that when H and S are small enough, Mathematica gives the correct eigenvalues (≈ ...
5
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1answer
234 views

Largest matrix size supported by Mathematica 10

I have need to store large square matrices in memory, some times sparse, some times not. I have used up to $2^{15}$ by $2^{15}$ as my upper bound so far, and Mathematica has handled it even if it took ...
1
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1answer
58 views

Defining a matrix with the symmetry Transpose[A(q)]=A(-q)

I am trying to construct a symbolic matrix with the following property- $$ \left(D_{3\times3}(q)\right)^T = D_{3\times3}(-q) $$ Note that for $q\in \mathbb{R}$, $D(q)$ would be hermitian. So far i ...
1
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1answer
97 views

Getting a part of a matrix Inverse for later use

I was trying to get an element of a matrix, and use in further computation of my program. Problem was that its not reading the value unless and until I specify it again. My code is: ...
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2answers
70 views

Insert an element to AdjacencyGraph

I'm not able to insert an element to mine AdjacencyGraph. I suppose that i should modify my AdjcencyMatrix: ...
1
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1answer
136 views

Why does Mathematica add Hold to the result of my user defined symbol?

In the code below I have defined a symbol that multiplies two block-matrices (I can't use the builtin Dot since Dot assumes that the matrix coefficients commute): ...
0
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1answer
69 views
4
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3answers
219 views

How can I suppress zero or nonzero values in a matrix?

So, if I have something like: F[IdentityMatrix[3] // MatrixForm, 1] I'd like F[] to display: $$\begin{pmatrix} 1 & ...
5
votes
4answers
269 views

Replacing parts of a matrix

I'm a beginner to Mathematica and to writing scripts in general. I'm currently trying to write a code that will take any element in a matrix higher than a certain threshold value n and set it equal to ...