Commutative linear operators and their properties

McLaren Rulez
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Can someone help me with this? When two linear operators commute, I know how to show that they must have at least one common eigenvector. Beyond this fact, what else can be said about commutative operators and their eigenvectors? Further, can they be diagonalized simultaneously (or actually, can they be diagonalized in the first place?), and if so, how can this be proved?
 
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I wished to know about this but no one is responding to this thread. Please, can one somebody help?
 
kthouz said:
I wished to know about this but no one is responding to this thread. Please, can one somebody help?

Well, what have you thought about so far? Take 2x2 matrices. Can you find one that can't be diagonalized?
 
kthouz, I asked this question again at https://www.physicsforums.com/showthread.php?t=501340

It was a mistake on my part as I had posted this in homework section instead of linear algebra where it belongs. That's why you are not getting replies. If you have a different question from what I asked in the link, try posting a new thread in the linear algebra section. You will definitely get help
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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