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sigmund
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I have this eigenvalue problem:
[itex] \frac{\mbox{d}^2y}{\mbox{d}x^2}+\left(1-\lambda\right)\frac{\mbox{d}y}{\mbox{d}x}-\lambda y = 0 \ , \ x\in[0,1], \ \lambda\in\mathbb{R}
[/itex]
[itex] y(0)=0 [/itex]
[itex] \frac{\mbox{d}y}{\mbox{d}x}(1)=0 [/itex]
Then, I have to show that there exists only one eigenvalue [itex] \lambda [/itex], and find this eigenvalue and write the corresponding eigenfunctions.
Thus far, I have solved the ODE's characteristic equation
[itex] r^2+(1-\lambda)r-\lambda=0 [/itex].
This gives me two solutions
[itex] r=-1 [/itex] and [itex] r=\lambda [/itex].
Thus the solution to the ODE is
[itex]
y=c_1\exp(-x)+c_2\exp(\lambda x) \ , \ x\in\mathbb{R} \ , \ c_1, \ c_2\in\mathbb{R}
[/itex].
Can I now conclude that because we only have real solutions to the characteristic equation, only one eigenvalue exists?
Secondly, I am not completely sure how to find the sought eigenvalue. I know how to find the eigenvalue when I have a solution that involves [itex] \sin [/itex] and [itex] \cos [/itex], but here I am not sure how to do it. Could anyone give me a hint?
Thirdly, when I have the eigenvalue there should not be any problems in writing the corresponding eigenfunctions, or is it?
I would appreciate any help. I am not looking for a solution to my homework problem, but any hints to the problem mentioned above are welcome.
[itex] \frac{\mbox{d}^2y}{\mbox{d}x^2}+\left(1-\lambda\right)\frac{\mbox{d}y}{\mbox{d}x}-\lambda y = 0 \ , \ x\in[0,1], \ \lambda\in\mathbb{R}
[/itex]
[itex] y(0)=0 [/itex]
[itex] \frac{\mbox{d}y}{\mbox{d}x}(1)=0 [/itex]
Then, I have to show that there exists only one eigenvalue [itex] \lambda [/itex], and find this eigenvalue and write the corresponding eigenfunctions.
Thus far, I have solved the ODE's characteristic equation
[itex] r^2+(1-\lambda)r-\lambda=0 [/itex].
This gives me two solutions
[itex] r=-1 [/itex] and [itex] r=\lambda [/itex].
Thus the solution to the ODE is
[itex]
y=c_1\exp(-x)+c_2\exp(\lambda x) \ , \ x\in\mathbb{R} \ , \ c_1, \ c_2\in\mathbb{R}
[/itex].
Can I now conclude that because we only have real solutions to the characteristic equation, only one eigenvalue exists?
Secondly, I am not completely sure how to find the sought eigenvalue. I know how to find the eigenvalue when I have a solution that involves [itex] \sin [/itex] and [itex] \cos [/itex], but here I am not sure how to do it. Could anyone give me a hint?
Thirdly, when I have the eigenvalue there should not be any problems in writing the corresponding eigenfunctions, or is it?
I would appreciate any help. I am not looking for a solution to my homework problem, but any hints to the problem mentioned above are welcome.
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