# Questions tagged [matrix]

Questions on the manipulation of matrices in Mathematica.

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### How to generate vectors with programming

I want to generate all possible vectors programicaly with entrys in $\Bbb Z_4$: $$A_j:=\begin{bmatrix}x_1\\ x_2\end{bmatrix}, \qquad x_i\in \{0,1,2,3\}, j=1,2,\cdots 16.$$
0answers
39 views

### How can I evaluate a symbolic matrix

For example if I have: Matriz = {{a, b}, {c, d}} Matriz2[a_, b_, c_, d_] := Matriz; when I run Matrix2 [1,2,3,4], the matrix is not evaluated. I would not like ...
0answers
27 views

### Problems with the parametric Recurrence Table

I am trying to construct a minimization program where I have to minimize a function with respect to a matrix. This matrix enters into the optimization program in a convoluted manner together with data....
2answers
81 views

### rule-based element selection from a matrix

For simplicity, I give a (3,3) matrix below, though my matrix is of a larger dimension. My objective is, after some matrix manipulations, to select Maximum element(s) in a row and a column, and place ...
1answer
52 views

### find a maximum parameter for a range of target eigenvalues as a function of matrix dimension

I have a symbolic tridiagonal matrix of this form ...
2answers
895 views

1answer
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### How to plot multiple functions in a graph with different colors?

I have a general {i,x,y} dimensional matrix, and I want to plot all "i" {x,y} matrices in one graph. How can I do it in a way that I can still distinguish each "i"th curve from the other (I mean ...
4answers
1k views

### Difficulty using LUDecomposition

I'm having trouble using LUDecomposition with pivoting. I read the Mathematica help on this particular command, but I'm still lost. Take a matrix like: ...
1answer
55 views

### How to carry a matrix in algebric form under “set delayed”

I have a small query and a related problem regarding the working methodology of Mathematica under set delayed/Do functions. Here is a simplified version of my problem. ...
1answer
76 views

### Find position equal columns of matrix

Consider the following rectangular matrix M = {{1,1,1,1},{2,2,4,4},{3,3,5,5},{9,9,3,1}} I would like to extract the position of equal columns. Is there a simple ...
0answers
34 views

### How to work with a $k$x$k$ matrix with $k$ undefined?

I have the following $k$x$k$ square matrix m: ...
1answer
83 views

### Compute the potential of confusion between 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 ...
1answer
21 views

### Eigenvalues and inverse of matrix which has matrix entries

Suppose I have a $2\times2$ matrix which contains $2\times2$ matrices as entries, is there a clean way to find the inverse of such object and compute its eigenvalues/vectors? My code is ...
0answers
30 views

### Simulating Stochastic Matrix Differential Equation with Arbitrary Autocorrelation Function

I want to numerically simulate a matrix differential equation that includes a stochastic (vector) Gaussian noise $\mathbf{n}$, where the different vector components are independent, and each component ...
4answers
212 views

### Manipulate a list: replace random position of a specific integer n times by 0

I have this matrix with 3 sublists: d = {{1, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0}, {0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1}, {0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0}}; For ...
0answers
34 views

### Matrix Vector multiplication [duplicate]

I have a rather simple question which surprisingly i could find the answer theres a matrix $U$ whith is $4*4$ and a vector $A$ which is $4*1$ and when I wand to multiply them by $U.A$ operator i get ...
3answers
393 views

### Create Array from list of indices/values

Is there is a performat way to convert something like {{0,0},a},{{0,1},c},{{1,0},d},{{1,1},e} into {{a,b},{c,d}} The ...
0answers
36 views

### How to save a all matrices renewed in each iteration?

I have a (n by m) matrix , in which the elements are recalculated and replaced by new ones in each iteration. (In other words I have a loop in which the elements of the mentioned matrix are being ...
2answers
162 views

### Multiply vectors in a matrix by a matrix

I have a matrix of vectors e.g. mat1 = Table[Table[RandomReal, 2], n, n]; which is actually a matrix of cartesian coordiantes ...
1answer
53 views

### MatrixConditionNumber does not work in version 12.0

A = {{1., 0.}, {0., 2.}}; LinearAlgebra`MatrixConditionNumber[A]
1answer
371 views

### Efficiently defining a SparseArray function

I've got a fairly large SparseMatrix (~60,000 entries in a ~10,000-by-10,000 matrix) that depends on two parameters (im1 and <...
3answers
571 views

### How to convert diagonal matrix to rectangular matrix

Suppose you have the following diagonal matrix: $\left( \begin{array}{cc} a & 0 \\ 0 & \{b,c\} \end{array} \right)$ How can the above matrix be converted to the following rectangular one?...
5answers
1k views

### How can I define a very large matrix efficiently?

Here's a 7x7 matrix: ...
1answer
33 views

### Identification of linear combinations in a matrix

I have a matrix R which is having a dimension of 20 cross 20. When I extracted the rank of this matrix I got 16. I just wanted to which are these four rows are or columns which are dependent on each ...
0answers
54 views

### Matrix transformation

Let an expression $X^T AX+B^TX$, how can I transform it as $Y^T C Y$; where $Y=[X, 1]$, find $C$ in terms of $A$ and $B$ using Mathematica?
2answers
116 views

### How to import latex matrices into Mathematica?

I have a lot of $\LaTeX$ matrices, and I want to find their eigenvalues and eigenvectors. I tried to import them to Mathematica with: ...
1answer
57 views

### Inverse matrix not computing [closed]

Hi just wondering why my Inverse of matrix will not compute? I don't believe its wrapped from //MatrixForm because I copied it by hand into a new document and it still would not work. Any ides? ...
0answers
38 views

### Why doesn't this evaluate further [duplicate]

The figure above shows the code as typed into Mathematica. In the fourth last line (or In as you prefer) the expression is not evaluated to the fullest extent possible. Why does this occur? I ...
2answers
59 views

### Error in Assignment

I want to create a matrix with each element updated as per the formula, whose inputs are dependent on the location of element in the matrix. ...
1answer
226 views