Green's Function on DE with variable coefficients

In summary: Your Name]In summary, the student is struggling with finding the Green's Function for a differential equation with variable coefficients in their Mathematical Physics course. They have tried using series, Frobenius method, and integral transforms but have not been successful. They are seeking advice on how to approach the problem and are encouraged to seek help from their instructor or a tutor.
  • #1
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Homework Statement


Hello. I'm taking a course on Mathematical Physics, based on Eugene Butkov's book. I'm having trouble solving a DE with variable coefficients to find Green's Function.

The problem asks to find Green's Function through direct construction.

Homework Equations


[tex] \frac{d}{dx} [ \frac{1}{x} \frac{dy}{dx} ] = f(x) [/tex]
[tex] 0 \leq x \leq 1 [/tex]
[tex] y(0) = y'(1) = 0 [/tex]

The Attempt at a Solution


I take it "through direct construction" means solving the system for G, replacing f(x) with the delta function. I've tried writing G(x,x') in series:

First, using a sine. The boundary conditions are satisfied, but when applying this G in the DE note that we get G'' and G', so there's a sine and a cosine and I can't use orthogonality to find the coefficients (that depend on x').

Then, I tried Frobenius method. And I get that all coefficients except for a0 are zero.

Any ideas on how to solve that equation? =(
 
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  • #2


Dear fellow student,

I understand your struggle with finding the Green's Function for a differential equation with variable coefficients. It can be a challenging task, but with the right approach, it is definitely achievable.

Firstly, I would suggest trying to solve the equation using the method of variation of parameters. This method involves finding a particular solution to the nonhomogeneous equation and then using it to construct the Green's Function. It may be helpful to review this method in your textbook or seek additional resources online.

Another approach you could try is using integral transforms, such as the Laplace transform or the Fourier transform. These transforms can help simplify the differential equation and make it easier to solve for the Green's Function.

Lastly, I would recommend seeking assistance from your instructor or a tutor if you are still having trouble. They can provide guidance and support to help you understand the concept better and find a solution to your problem.

I hope this helps and good luck with your studies!


 

1. What is a Green's Function on DE with variable coefficients?

A Green's Function on DE with variable coefficients is a mathematical tool used to solve a differential equation with varying coefficients. It is a function that satisfies a certain differential equation and allows for the solution of the original equation to be expressed as a linear combination of the Green's Function and its derivatives.

2. Why is a Green's Function useful for solving DE with variable coefficients?

A Green's Function allows for the solution of a differential equation with variable coefficients to be expressed in a simple and elegant form. It also provides a way to solve boundary value problems and initial value problems for the original differential equation.

3. How is a Green's Function calculated for a DE with variable coefficients?

The calculation of a Green's Function for a DE with variable coefficients involves finding a fundamental set of solutions for the homogeneous equation and using them to construct the Green's Function. This involves solving a system of linear equations and integrating the resulting solution.

4. Can a Green's Function be used for any type of differential equation with variable coefficients?

Yes, a Green's Function can be used for any type of differential equation with variable coefficients, including both ordinary and partial differential equations. However, the method for calculating the Green's Function may vary depending on the specific type of equation.

5. Are there any limitations to using a Green's Function for solving DE with variable coefficients?

While a Green's Function is a powerful tool for solving DE with variable coefficients, it does have some limitations. It may not be applicable for all types of boundary value problems, and the calculation process can become complex for higher order differential equations.

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