Solving Boundary Value Problems: Are Eigenvalues Equal?

In summary, the conversation discusses two boundary value problems with different boundary conditions but the same homogenized ODE. The question is whether the eigenvalues for both cases are equal or have the same dependence on the parameter 'n'. The answer is that in general, the eigenvalues will be different due to the different characteristic equations, but the specific details of the problem may result in the eigenvalues being equal.
  • #1
zetafunction
391
0
let be the two boundary value problem

[tex] -D^{2}y(x)+f(x)y(x)= \lambda _{n} y(x) [/tex]

with [tex] y(0)=0=y(\infty) [/tex]

and the same problem [tex] -D^{2}y(x)+f(x)y(x)= \beta _{n} y(x) [/tex]

with [tex] y(-\infty)=0=y(\infty) [/tex]

i assume that in both cases the problem is SOLVABLE , so my question is , are the eigenvalues in both cases equal ? , i mean [tex] \lambda _{n} = \beta _{n} [/tex] , or have the same dependence on parameter 'n' ?
 
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  • #2
I don't understand your notation. You first homogenize your ODE, then you find the eigenvalues of your characteristic equation. Then you apply BCs to extract constants of integration. So you find eigenvalues before applying BCs. So, in general, yes.

However, the way you have described your equations, your characteristic equation will be different, so different eigenvalues. So if I don't understand your query, then my answer is probably wrong.
 

Related to Solving Boundary Value Problems: Are Eigenvalues Equal?

1. What is a boundary value problem?

A boundary value problem is a type of mathematical problem that involves finding a solution to a differential equation that satisfies certain conditions or constraints at different points or boundaries.

2. What are eigenvalues and how are they related to boundary value problems?

An eigenvalue is a special type of value that is associated with a mathematical object, such as a matrix or differential operator. In the context of boundary value problems, eigenvalues are important because they determine the possible solutions to the problem and can help in finding the most suitable solution.

3. What does it mean for eigenvalues to be equal in a boundary value problem?

When eigenvalues are equal in a boundary value problem, it means that there are multiple solutions to the problem that satisfy the given conditions. This can happen when the boundary conditions are not enough to uniquely determine the solution or when the problem has a symmetry that leads to repeated eigenvalues.

4. How can eigenvalues be used to solve boundary value problems?

Eigenvalues can be used to solve boundary value problems by providing a set of values that can be used to construct the solution. By finding the eigenvalues, one can determine the general form of the solution and then use the boundary conditions to determine the specific values of the solution.

5. Are there any limitations to using eigenvalues to solve boundary value problems?

Yes, there are limitations to using eigenvalues to solve boundary value problems. For example, it may not always be possible to find the eigenvalues analytically, and numerical methods may need to be used. Additionally, some boundary value problems may have non-unique solutions or no solutions at all, making it difficult to use eigenvalues to find a suitable solution.

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