# Tagged Questions

Questions on the manipulation of matrices in Mathematica.

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### 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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### 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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### 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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### Solving Symbolically Equations with Vectors and Matrices [closed]

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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### Replace part of a matrix

I have to generate a ne numbers of matrices with 1 and 0 and then replace some elements. ...
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### 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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### 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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### 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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### 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 ...
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### 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: ...
1k 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: ...
2k 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 ...
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### 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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### 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. ...
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### Does Mathematica support Laguerre Polynomials of Matrix Argument? [duplicate]

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: http://www.jstor....
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### 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 (≈ -1,-...
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### 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 ...
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### 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 ...
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### 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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### Insert an element to AdjacencyGraph

I'm not able to insert an element to mine AdjacencyGraph. I suppose that i should modify my AdjcencyMatrix: ...
192 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): ...
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### Difference Eigenvector values in mathematica 9 and mathematica 10 [duplicate]

I have the following matrix; ...
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### 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 & &...
291 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 ...
320 views

### I need some GPU benchmark for Mathematica [closed]

I am considering to buy a GPU. I need to know two things: Is it possible to solve a system of differential equations using GPU and Mathematica's functions? I need to know how much faster would be ...
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### 'MatrixForm' problem [duplicate]

I prefer to use 'MatrixForm' because the form looks better in matrix manipulation. But my current problem is that after the use of 'MatrixForm', subsequent matrix calculations like 'Det' or 'Inverse' ...
166 views

### Calculate efficiently an expensive hermitian matrix

I want to compute a matrix $M_{pq}$, for which the calculation of each coefficients $M_{pq} = f(p,q)$ is an expensive function. I know that my matrix is hermitian, so that $M_{qp} = M_{pq}^{*}$. As a ...
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### specified matrix query

can you tell me a way (best?) to get a matrix with i=N,j=N dimensions (quadratic) according to the following rules: variables: N , M, n the diagonal must contain zeros it must contain exactly M ...
315 views

### Table and memory efficiency

Consider these two types of creating matrices: Table[Table[i*j,{i,1,10}],{j,1,10}] Table[i*j,{i,1,10},{j,1,10}] I want to know if there is any difference ...
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### Fast matrix multiplication in MMA and GPU

Matlab multiplies two 3000by3000 matrix around 0.18s faster than MMA. While for just a few matrix multiplications the speed difference is not important, it becomes crucial when I want to do those ...
3k views

### How to take transpose of a one dimensional vector? [closed]

Why the two followings giving me same output? At least one should give me a row vector and another should give me a column vector. ...
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### Structure analysis based on direct stiffness method. Solve taking too much time

The program generates a very large matrix based on some input from the user. The matrix is symmetric and called generalstifnessmatrix. It also generates 2 other lists(displacement and forces list) ...
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### Multiplying block matrices

I have a 2*8 matrix A, and a 2*8*2 matrix B. So B[[1]] and B[[2]] are both 8*2 matrices. I need a neat way to multiply A by B so that the first list in the result is A.B[[1]] and the second list ...
293 views

### Rescaling and reorienting Matrix Plot axes

I have implemented a numeric Laplace Solver in C++ and am trying to graphically represent the validity of my method. I have outputted the grid from C++ and imported it into Mathematica to get the ...
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### Obtaining the relations of variables using diagonal matrices

I know this is too an elementary question, but I am a pathetic newbie in mathematica and I cannot find any answer by googling. What I want is obtaining some relations of unknown variables using their ...
197 views

### Print array with indices

Is there a single function that prints an array together with the indices? I know how to achieve this with Grid[{Range[n],array},Frame->All], but I vaguely ...
103 views

### solving singular matrix [duplicate]

Hello I have a matrix that is singular, and i wanted to use linear solve to solve it but that doesn't work with mathematica. The matrix given as a list looks like this: ...
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### parsed matrix not deleting elements in adjusted matrix

I have a matrix that has been parsed to delete certain rows and columns, as well as delete certain elements on the diagonal on the matrix. The problem is that it does this in theory when i take the ...
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### Matrix form of complex numbers [closed]

Complex numbers have matrix form. But some 2x2 matrices while differ, represent the same complex number. To compare complex numbers one has to transform the matrices to the form \begin{pmatrix} a &...
230 views

### Design matrix rank does not match

I'm attempting to fit a linear model and Mathematica returns the error message: "The rank of the design matrix 9 is less than the number of terms 10 in the model. The model and results based upon it ...
243 views

### How to reflect the entries of a square matrix about its anti-diagonal?

I need help with writing the mathematica code to reflect the entries of a square matrix about its anti-diagonal. I know to do it about the main diagonal using ...
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### Why is there a seeming discrepancy with the expression Cofactor?

I was trying to find out the cofactors of a square matrix. Then I came across the command Cofactor in Combinatorica package. ...