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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.

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How to plot an eigenspectrum in python?

This is what I have tried: # Show the eigenspectrum eigenvalues = pca.explained_variance_ print("The eigenvalues:\n\t", eigenvalues) idx = eigenvalues.argsort() print(idx) plt.plot(idx, color='green',…
user4476006
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CImg and Eigen, eigenvalues coming up all the same values

I am using CImg and the Eigen library for a facial recognition project. I have everything (seemingly) working up until the point where i generate the eigenvalue vector. Then all values come up as the same (-6.27744e+066), which is obviously…
CChiste
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PCA - Relation Between Variance of Eigen values and the effectiveness of PCA on the data

If the covariance matrix has eigenvalues λ1 ≥ λ2 ... ≥ λd > 0 why is the variance of the eigen values, a measure of whether or not PCA would be useful for analyzing the data (the higher the value of σ the more useful PCA).
Vivek Aditya
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Convergence criteria for scipy.eigvalsh

I am using python (scipy) to compute eigenvalues of a symmetric real matrix. I am currently using the scipy.linalg.eigvalsh function to compute the eigenvalues…
TravisJ
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Finding Eigenvalue and Eigenvector of a symmetric n*n matrix in Matlab

I need to find the eigen value decomposition of the symmetric matrix in Matlab. But I do not want to use the matlab inbuilt function eig Can anyone tell me efficient algortihm. I have already implemented the power Iteration Algorithm but it is not…
mangleshwar srivastava
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Finding the Associated Eigenvector in Matlab

For this problem, I think I got most of code correct. However, the correct eigenvector contains the negative values of what I have. The instructions: My code: clear all; close all; M = [0 1/4 1/4 0 0 0 0 0 0 0; 1/2 0 1/4 1/4 1/6 0 0 0 0 0; …
Jack L.
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how to solve this matrix equation? eigen vector?

I have the following equation. How can I solve it? AW = BW Where A,B,W are MATRICES. B is invertible. Any hint to solve it in Matlab?
user570593
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Finding all complex eigenvalues near the unit circle of a large matrix (n around 10k-100k) with MATLAB

I am studying wave propagation in periodic material and need to computes slowness surfaces which are obtained by computing polynomial eigenvalues of some matrix. Given that I am only interested in propagative waves, only eigenvalues near the unit…
Redg
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Difference between R and eigen3

I perform the following in R: > m = matrix(c(0.563291, -0.478813, 0.574175, + 0.160779, -0.03407, 0.381922, + 0.0677914, 0.870361, -0.88602), 3, 3) > mt = t(m) > mt [1,] 0.5632910 -0.478813 0.574175 [2,] 0.1607790 -0.034070 0.381922 [3,]…
Ivan
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Hopefully Quick Parallel Optimal Lapack Routine (gfortran) Questions

I thought I had a very clear understanding of this until two days ago, but now I might be over thinking it and confusing myself. I'll explain what I'm doing and then ask a couple of probably simplistic questions, but I've searched and found…
Nick Oliviero
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ARPACK gives different answers from Matlab and NAG

I'm playing with ARPACK. I looked into the examples they provide, zndrv4.f, in the ARPACK/EXAMPLES/COMPLEX/ directory. I also came cross into NAG Fortran Library. In NAG, there are some linear problem solvers F12***. The F12*** routines in NAG are…
jengmge
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Finding eigenvalues in a loop matlab

Ok this is how it's supposed to work. In the while loop eigenvalues are calculated for the increments of U in the variable lambda. The idea is to break the while loop once a real part of a variable lambda becomes positive and return the value of U…
TomM
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Sort complex vectors in specific order

I have vector with eigenvalues: e = -0.4094 + 3.9387i -0.4094 - 3.9387i -0.0156 + 0.5645i -0.0156 - 0.5645i And I would like to sort this vector like that: e_sort = -0.0156 + 0.5645i -0.4094 + 3.9387i -0.0156 - 0.5645i -0.4094 - 3.9387i The…
MrPitivier
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C++: how to sort a complex matrix based on real parts of a complex vector

I have a complex vector (VSII_Complex containing Eigen values) and a complex matrix (CUII_Complex containing Eigen vectors). Each element of VSII_Complex is corresponding to a column of CUII_Complex. My problem is that I want to sort the Eigen…
Megidd
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How to solve a generalized eigenvalue Problem for multiprecision in Python

I want to solve a generalized eigenvalue problem for multiprecision in Python ( A.C = (lam).B.C where A and B are 3000x3000 matrices and C is 3000x1 vector. (lam) is the eigenvalue.). So I have installed MPMATH. But I can't find a Python program for…
Yılmaz Eser
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