Understanding Eigen Functions: A Beginner's Guide

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Eigenfunctions, eigenvectors, and eigenvalues are fundamental concepts in linear algebra and functional analysis, often applied in differential equations. The discussion highlights a specific example involving the function sinh(2x) and its relation to the second derivative operator, emphasizing that while d²/dx²(sinh(2x)) = 4sinh(2x), sinh(2x) is not classified as an eigenfunction of that operator. The importance of these concepts extends beyond quantum mechanics to various fields of applied mathematics. Participants are encouraged to explore resources to deepen their understanding and to seek further clarification if needed. Engaging with these ideas is essential for grasping their applications in mathematical contexts.
Alekside
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Hello
today i learn about Eigen Function, I have many problem about Eigen Fuction

I not understand what the Eigen Fuction, Eigen Vector, Eigen Value?

For Example I not Understand this problem,
show the sinh 2x as not a Eigen Function d2/dx2, Although the equation as d2/dx2 sinh2x = 4 sinh 2x
 
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Its a concept from linear algebra, but via that wondrous subject known as functional analysis :p:p:p:p:p, and that the solutions of differential equations form a vector space, and indeed functions with rather weak crireria such as being square intergrable, also form a vector space, it is carried over to that as well:
http://tutorial.math.lamar.edu/Classes/DE/BVPEvals.aspx

Hopefully the above link will allow you to nut it out.

Its well worth your time as, not just in QM, but in applied math in general, its an EXTREMLY important copncept.

Thanks
Bill
 
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well thanks verry much bill, I will read a minute about QM, so thanks
 
Alekside said:
well thanks verry much bill, I will read a minute about QM, so thanks

No problem.

If you are still having problems do post back - on this or any issue.

It fairly easy to actually do your question, but its a lot better if you nut it out and do it.

Thanks
Bill
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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