Which is the Correct Jordan Form?

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In summary, the conversation discusses the concept of a Jordan Form in a textbook. The speaker is confused about why one of the matrices is not listed as a Jordan Form and asks for clarification on which property to check for. Another speaker suggests that the textbook may be requiring a specific order for the Jordan blocks, but this is not a standard convention. The original speaker confirms that this is the case in the textbook, but it should have been made clearer.
  • #1
arthurhenry
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In the book I am looking only one of the following is listed as a Jordan Form. Could somebody tell me why the other one is not (that is, if I were confused again, which property of a Jordan Form I should check and decide on the correct one)
Thank you

210 200
020 021
002 002
 
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  • #2
Hi arthurhenry! :smile:

Those both look like Jordan forms to me. Did the book specifically say that the other one wasn't a Jordan form?
 
  • #3
It is possible that, in order to make the "Jordan Form" unique", your textbook is requiring that "Jordan blocks" come before "isolated" eigenvectors. But that is not standard.
 
  • #4
HallsofIvy said:
It is possible that, in order to make the "Jordan Form" unique", your textbook is requiring that "Jordan blocks" come before "isolated" eigenvectors. But that is not standard.

That sounds about right.

Look at the definition in your book of a Jordon block matrix, does he say anything about the placement of Jordan blocks according to their multiplicities?
 
  • #5
Sorry for the late response, and I thank you all. Yes, I did find such a convention in the book.
So this should mean that I can show those two Jordan Forms are "the same", similar ?
I will try to show that now.
Thank you
 
  • #6
Yes, because if you rearrange the Jordan blocks, then you just have to rearrange the corresponding eigenvectors in the similiarity matrix, so this definition where he requires the Jordan blocks to be placed in a certain order is a bit stupid for this exact reason.

Fine, if it lends itself to a certain formalism but he should have made it clear in the text that the order does not matter, and by setting this question, he clearly has failed to do so.
 

1. What is the Jordan form of a matrix?

The Jordan form of a matrix is a special type of matrix that has a specific structure and is used to represent linear transformations. It is named after the mathematician Camille Jordan and is useful in understanding the properties and behavior of a linear transformation.

2. How do you find the Jordan form of a matrix?

To find the Jordan form of a matrix, you need to perform a process called Jordan decomposition. This involves finding the eigenvalues and eigenvectors of the matrix and then arranging them in a specific way to form the Jordan form. This process can be quite complex and may require advanced mathematical techniques.

3. What is the significance of the Jordan form?

The Jordan form is significant because it allows us to understand the behavior of a linear transformation in a simpler and more organized way. It also helps in solving systems of linear equations, computing matrix powers, and determining the stability of a system.

4. Can any matrix have a Jordan form?

No, not all matrices have a Jordan form. Only square matrices that satisfy certain conditions can have a Jordan form. These conditions include having distinct eigenvalues and being diagonalizable.

5. How is the Jordan form different from the diagonal form?

The Jordan form and diagonal form are both ways of representing a matrix, but they differ in terms of their structure. The Jordan form is a block diagonal matrix, where each block represents a Jordan block. In contrast, the diagonal form is a diagonal matrix, where all the entries outside the main diagonal are zeros. Additionally, the diagonal form can only be obtained for matrices with distinct eigenvalues, while the Jordan form can be obtained for matrices with repeated eigenvalues.

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