Stack Overflow
Stack Overflow

Questions tagged [eigenvalue]

The eigenvalue is the factor by which the eigenvector is scaled when multiplied by the matrix.

The eigenvectors of a square matrix are the non-zero vectors that, after being multiplied by the matrix, remain parallel to the original vector. For each eigenvector, the corresponding eigenvalue is the factor by which the eigenvector is scaled when multiplied by the matrix. The prefix eigen- is adopted from the German word "eigen" for "own"[1] in the sense of a characteristic description. The eigenvectors are sometimes also called characteristic vectors. Similarly, the eigenvalues are also known as characteristic values.

Find more on this topic on Wikipedia

747 questions
0
votes
1 answer

How can I create a plot of eigenvalues in R?

I need to create a plot in R of the following eigenvalues: 2.2928, 0.401, 0.1322, 0.0594, 0.0406, 0.0288, 0.025 at Principal Components 1-7. I used the following dataset: Chu_data =…
Victoria447
  • 11
  • 1
  • 2
0
votes
1 answer

Eigenvector of matrix computed by Python does not appear to be an eigenvector

Apologies in advance, Python is not my strong suit. The eigenvector corresponding to the real eigenvalue of this matrix (as computed by Python) does not appear to be an eigenvector, whereas the eigenvector as computed by Wolfram Alpha appears to…
helen
  • 3
  • 2
0
votes
1 answer

Getting the eigenvalues in a list from a list of matrices

I want my code to prompt the user for a list of eigenvalues, run through every possible 0,1 matrix with that number of vertices, create a list of all possible eigenvalues, and if any match what the user puts in, it returns the corresponding matrix.…
CharlesLyleLarue
  • 3
  • 2
0
votes
1 answer

Simple Eigenvalue Idea

I have a vector Nx1 with numbers that I want to be the eigenvalues of a matrix X which I am attempting to construct. Essentially, I want to take my Nx1 matrix and list the ith entry of this vector on the ith diagonal of this matrix. I have tried…
I Like When Things Get Complex
  • 3
  • 1
0
votes
1 answer

How does scipy.linalg.eigvals actually calculate eigenvalues?

I can't find any documentation on how this thing actually calculates eigenvalues, the documentation just says it uses '_geev LAPACK routines', but I have searched and searched for documentation on that and can't find it either. Getting weird links…
jcm
  • 205
  • 3
  • 7
0
votes
0 answers

Solving eigenvalue linear system with Fortran using Lapack zggev routine

I am trying to use the ZGGEV routine from Lapack to solve the general eigen value problem, namely, A x=v B x. Where v is the eigen-value. I'm doing a small test on some random matrixes. Let's say A=[ -21.10-22.50i 53.50-50.50i -34.50+127.50i …
Huang Wei
  • 39
  • 3
0
votes
1 answer

python: Modifying eigenvectors based on multiplicity of eigenvalues

For a given matrix A with eigevalues eigval and eigevectors eigvec, here's what I want to do: Find the eigenvalues with multiplicity > 1 Find the corresponding eigenvectors. Perform some calculations on these eigenvectors Create eigvec with these…
thorium
  • 187
  • 8
0
votes
1 answer

Strange behaviour of ARPACK for hermitian matrix

I want to obtain numerically the energy of the ground state of some hermitian matrix (see the definition of this matrix in the following code) and plot it in terms of the matrix-parametter "phase". import scipy.sparse as sparse import scipy import…
Joe
  • 189
  • 10
0
votes
1 answer

How to compute the first eigenvalue and eigenvector in Fortran

I tried to use ARPACK using some examples (here), but I could not even figure out how to input my matrix. From this question, It seems that the implementations in Python and Matlab are the only solution to avoid the complexity of ARPACK. Is there…
Garini
  • 1,088
  • 16
  • 29
0
votes
1 answer

How can I use Armadillo to compute eigenpairs?

I just got Armadillo and wanted to familiarized myself so I am doing a "test" run with it int main(){ double myMatrix[6][6]; for (int i = 0; i < 6; i++){ for (int j = 0; j < 6; j++){ myMatrix[i][j] = i+2*j; } …
user355843
  • 53
  • 1
  • 1
  • 8
0
votes
1 answer

How many PCA axes are significant under this broken stick model?

Following the usual methodology I have created a screeplot to assess how many principal component axes are significant. However, the broken stick is greater than the variance for PC3 and PC4 but not PC2. Is only PC1 significant under the broken…
steve24
  • 35
  • 3
0
votes
1 answer

Minimise (optimise) particular eigenvalue in Python

I have written a simple Python code that reads arrays from a file. All the array elements contain basic algebraic operations (e.g. y*w+2*(w+y)). These are read in, and then all the array elements are evaluated using the eval command (I know the…
Yeti
  • 425
  • 4
  • 15
0
votes
0 answers

Eigenvalue eigenvector extraction routine

I need to extract the lowest, e.g., 30 eigenvalues and their eigenvectors from a real symmetric sparse double-precision matrix which has a size about 200k x 200k. I know it's huge (about 310 GB if they are 8-byte doubles) but I have enough RAM for…
Yuhong
  • 158
  • 3
  • 9
0
votes
0 answers

Wrong eigenvalues with GSL

The eigenvalues I obtain are different for GSL (Gnu Scientific Library) and for Matlab. Can someone give me a hint what I am doing wrong? : #include #include #include #include…
Ulli
  • 11
  • 3
0
votes
2 answers

Do we need to normalize the eigen values in Matlab?

When using eig function in Matlab, it seems that this function has already normalize the values of the eigenvalues. Do we need to write some lines of code to normalize the eigenvalues after using the eig function.
kgk
  • 649
  • 1
  • 10
  • 23
1 2 3
…
49 50