# Questions tagged [matrix]

Questions on the manipulation of matrices in Mathematica.

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28 views

### Create symmetric array of function values

I have function B[i,j] where i,j are integers. Then I create array: b = Array[B, {3,3}] now I set values of ...
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### easiest way to construct the following determinant

What is the easiest way to construct the following determinant?] p is variable, I want to vary value of p each time and get the appropriate determinant.
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### How to select multi vectors with particular condition

I have a matrix as: a01={{225., 1, 2, 3, 4}, {225.5, 2, 3, 4, 5}, {226., 3, 4, 5, 6}, {226.5, 4,5,6,7}} And I want to choose head: ...
417 views

### Defining a big matrix for iterative algorithm

I need to solve this system of equations with Seidel and Jacobi methods, so I tried to define a big matrix in Wolfram. I have read documentation, and I wrote the following command that should help me,...
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### How to remove curly brackets in a two dimensional array near the edges?

Suppose I have a matrix {{1,2,3},{4,5,6}}. I want to remove the curly brackets near the edges, i.e., I want an output as '{1,2,3},{4,5,6}'. Somebody please help me to solve it.
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### Getting a non zero determinant of matrix R, when the Rank of R is not equal to Dimension of R

I have a square matrix whose dimensions is 9 cross 9, when I extract the rank of the matrix R, I am getting rank as 6. I have constructed R matrix by minimizing the Lagrangian Lg with respect to a[1].....
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### Numerically solve system of 64 equations with 64 variables in matrix form

I have 2 matrix $A$ and $B$ both of size 16x16. Most of the values $A_{i,j}$ and $B_{i,j}$ for the same couple $(i,j)$ are equal to 0. The remaining ones are a positive floating number for $A$ and a ...
31 views

### How to minimize the eigenvalues of a hermitian matrix?

Suppose I have a complex hermitian matrix, M[x_,y_] whose eigenvalues must be real.I tried to minimize the first eigenvalue by writing following command:f[x_,y_]:=Eigenvalues[M[x,y]][[1]]; Minimize[f[...
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### MatrixForm a product of matrices [closed]

I was hoping that MatrixForm[SingularValueDecomposition[{{1, 2}, {3, 4}}] ] would neatly display the singular value decomposition of a matrix in the form of a ...
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### diagonalisation of systems of symbolic equations from two cross products

A description of what I'm attempting: Given a generic vector $\vec{r}$ and a point in space $D$, I want to build a reference frame centred in $\vec{r}= (x,y,z)$, with one axis directed along the ...
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### Getting scores from PCA

I'm not super familiar with Principal Component Analysis, but from what I understand, it sorts a vector in order of decreasing variance, and uses that to transform the vector to correlate variables ...
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### Improve speed of NIntegrate for functions which are sums of complex exponentials

I need to improve the efficiency for numerically evaluating a matrix element, which uses NIntegrate of the several functions (which are all sums of complex exponentials). Creating the functions from ...
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### What row do I change to make my determinant non zero?

I wish to make a matrix that has an inverse. I need rows that look like oscillating functions so I decided to base my matrix on ChebyshevT. This code makes an n by ...
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### Take $n^\text{th}$ sub-list with equal distances

I have been looking at Span, Take, etc. functions but I couldn't figure out how can I extract elements likes this ...
I am trying to compute the null space of a large $n\times n$ sparse matrix. No matter how large the dimension of the matrix is, it will always look like as below: The figure on the left shows the ...