3x3 similar matrices defined by characteristic and minimal polynomials

In summary, a 3x3 similar matrix is a square matrix with dimensions of 3 rows and 3 columns that shares the same eigenvectors and eigenvalues with another matrix, but may have different bases and dimensions. Similar matrices are defined by their characteristic and minimal polynomials, which can be used to find eigenvalues and determine if two matrices are similar. However, two matrices can have the same characteristic and minimal polynomials but not be similar if they have different bases and dimensions. Similar matrices are important because they preserve the geometric structure of a vector space and have similar properties, making them useful in solving problems involving linear algebra.
  • #1
JamesTheBond
18
0
Why do you guys think that given two 3x3 matrices, they are similar if and only if their characteristic polynomial and minimal polynomial are equal (this reasonably fails for 4v4 matrices though)?
 
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  • #2
Just consider the Jordan Blocks
 
  • #3
Not exactly sure what you mean. How do Jordan blocks get involved?
 
  • #4
Jordan blocks are what describe matrices up to conjugacy. In a 3x3 matrix there are very few ways to decompose as Jordan block matrices, which answers your question as to why 3x3 (and 2x2) matrices are completely determined by their minimal polynomials.
 

1. What is a 3x3 similar matrix?

A 3x3 similar matrix is a square matrix with dimensions of 3 rows and 3 columns, where each element in the matrix corresponds to a specific coordinate in a three-dimensional space. Similar matrices share the same eigenvectors and eigenvalues, but may have different bases and dimensions.

2. How are similar matrices defined by characteristic and minimal polynomials?

The characteristic polynomial of a matrix is a special polynomial that can be used to find the eigenvalues of the matrix. The minimal polynomial is the smallest polynomial that when substituted into the matrix, results in the zero matrix. Similar matrices have the same characteristic and minimal polynomials, making them easily identifiable.

3. Can two matrices have the same characteristic and minimal polynomials but not be similar?

Yes, it is possible for two matrices to have the same characteristic and minimal polynomials but not be similar. This occurs when the matrices have different bases and dimensions, which means they do not share the same eigenvectors and eigenvalues.

4. How do you determine if two 3x3 matrices are similar?

To determine if two 3x3 matrices are similar, you can compare their characteristic and minimal polynomials. If they are the same, then the matrices are similar. You can also check if the matrices have the same eigenvalues and eigenvectors, as similar matrices share these properties.

5. Why are similar matrices important?

Similar matrices are important in linear algebra because they represent transformations that preserve the geometric structure of a vector space. This means that similar matrices share the same eigenvectors and eigenvalues, making it easier to analyze and solve problems involving these matrices. They also have similar properties, such as trace and determinant, which can be useful in various applications.

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