How Does a Non-Negative Matrix Ensure a Positive Eigenvector?

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In summary, if A≥0 and Ak>0 for some k≥1, then A has a positive eigenvector according to the Perron-Frobenius theorem.
  • #1
BrainHurts
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Homework Statement


If A≥0 and Ak>0 for some k≥1, show that A has a positive eigenvector.



Homework Equations





The Attempt at a Solution


A is nxn

Well from a previous problem we know that the spectral radius ρ(A)>0

We also know that if A≥0, then ρ(A) is an eigenvalue of A and there is a non negative vector x, x=/=0 such that Ax=ρ(A)x

Kinda stuck
 
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  • #2
What do you mean with a "nonnegative vector" or "positive vector"?
 
  • #3
non negative vector means all the entries in that vector is greater than zero,

if the vector is positive all entries in that vector is positive

i.e. if x≥0 all components of x are greater than or equal to zero

similarly if a matrix A≥0

all [aij]≥0

positive just means everything is greater than 0
 
Last edited:
  • #4
BrainHurts said:

Homework Statement


If A≥0 and Ak>0 for some k≥1, show that A has a positive eigenvector.



Homework Equations





The Attempt at a Solution


A is nxn

Well from a previous problem we know that the spectral radius ρ(A)>0

We also know that if A≥0, then ρ(A) is an eigenvalue of A and there is a non negative vector x, x=/=0 such that Ax=ρ(A)x

Kinda stuck

Google Perron-Frobenius theorem.
 

1. What are non-negative matrices?

Non-negative matrices are matrices where all elements are equal to or greater than zero. In other words, there are no negative numbers in the matrix.

2. What are the applications of non-negative matrices?

Non-negative matrices have a wide range of applications in fields such as computer science, economics, biology, and social sciences. They are often used to model and analyze complex systems, such as transportation networks, social networks, and biological processes.

3. How are non-negative matrices different from regular matrices?

The main difference between non-negative matrices and regular matrices is the restriction on the values of their elements. While regular matrices can have positive, negative, and zero elements, non-negative matrices can only have elements that are equal to or greater than zero.

4. Can non-negative matrices have negative eigenvalues?

No, non-negative matrices cannot have negative eigenvalues. This is because the eigenvalues of a non-negative matrix must be equal to or greater than zero, since the elements of the matrix are also non-negative.

5. How are non-negative matrices useful in data analysis?

Non-negative matrices are useful in data analysis as they can be used for dimensionality reduction and data clustering. They can also be used in the process of data decomposition, where a larger dataset is broken down into smaller, non-negative matrices for easier analysis and interpretation.

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