# What is the method of eigenfunction expansion?

## What is the method of eigenfunction expansion?

Central to the eigenfunction expansion technique is the existence of a set of orthogonal. eigenfunctions that can be used to construct solutions. For certain families of two-point. boundary value problems there are theorems that prove the existence of sets of orthogonal. eigenfunctions.

### What is Green’s function method?

In mathematics, a Green’s function is the impulse response of an inhomogeneous linear differential operator defined on a domain with specified initial conditions or boundary conditions.

#### What are eigenfunctions and eigenvalues?

When an operator operating on a function results in a constant times the function, the function is called an eigenfunction of the operator & the constant is called the eigenvalue. i.e. A f(x) = k f(x) where f(x) is the eigenfunction & k is the eigenvalue. Example: d/dx(e2x) = 2 e2x.

**How do you solve the Sturm Liouville problem?**

These equations give a regular Sturm-Liouville problem. Identify p,q,r,αj,βj in the example above. y(x)=Acos(√λx)+Bsin(√λx)if λ>0,y(x)=Ax+Bif λ=0. Let us see if λ=0 is an eigenvalue: We must satisfy 0=hB−A and A=0, hence B=0 (as h>0), therefore, 0 is not an eigenvalue (no nonzero solution, so no eigenfunction).

**What is Green function in integral equation?**

The Green’s function integral equation method (GFIEM) is a method for solving linear differential equations by expressing the solution in terms of an integral equation, where the integral involves an overlap integral between the solution itself and a Green’s function.

## What is green formula?

The Green formulas are obtained by integration by parts of integrals of the divergence of a vector field that is continuous in ¯D=D+Γ and that is continuously differentiable in D.

### How do you find eigenfunctions from eigenvalues?

The corresponding eigenvalues and eigenfunctions are λn = n2π2, yn = cos(nπ) n = 1,2,3,…. Note that if we allow n = 0 this includes the case of the zero eigenvalue. y + k2y = 0, with solution y = Acos(kx) + B sin(kx), and derivative y = −Ak sin(kx) + Bk cos(kx).

#### Which of the following functions is an eigenfunction of the operator?

Answer. Which of the following is Eigen function of D DX? The function eax is aneigenfunction of the operator d/dx because (d/dx)eax ¼ aeax, which is a constant (a) multiplying the original function. The constant o in an eigenvalueequation is called theeigenvalue of the operator O.

**What do you mean by eigenfunction?**

In mathematics, an eigenfunction of a linear operator D defined on some function space is any non-zero function in that space that, when acted upon by D, is only multiplied by some scaling factor called an eigenvalue.

**What is Eigen value and eigen function in quantum mechanics?**

The function is called an eigenfunction, and the resulting numerical value is called the eigenvalue. Eigen here is the German word meaning self or own. It is a general principle of Quantum Mechanics that there is an operator for every physical observable. A physical observable is anything that can be measured.

## How do you find the eigenvalue from eigenfunction?

### What are the eigenvalues and eigenfunctions of the Sturm-Liouville problem?

The problem of finding a complex number µ if any, such that the BVP (6.2)-(6.3) with λ = µ, has a non-trivial solution is called a Sturm-Liouville Eigen Value Problem (SL-EVP). Such a value µ is called an eigenvalue and the corresponding non-trivial solutions y(.; µ) are called eigenfunctions.

#### Is Green function continuous?

Green function for ordinary differential equations. The Green function of L is the function G(x,ξ) that satisfies the following conditions: 1) G(x,ξ) is continuous and has continuous derivatives with respect to x up to order n−2 for all values of x and ξ in the interval [a,b].

**What is extended Green’s theorem?**

This form of the theorem relates the vector line integral over a simple, closed plane curve C to a double integral over the region enclosed by C. Therefore, the circulation of a vector field along a simple closed curve can be transformed into a double integral and vice versa.

**How do you solve Greens Theorem?**

Along C2, y=0, so that F(x,y)=(y2,3xy)=(0,0). Consequently, ∫C2F⋅ds=0. Putting this all together, we verify that ∫CF⋅ds=∫C1F⋅ds+∫C2F⋅ds=23+0=23. Our direct calculation of the line integral agrees with the above result that we obtained by applying Green’s theorem to convert the line integral to a double integral.

## What is eigenvalue eigenfunction?

### How do you normalize an eigenfunction?

Depending on whether the spectrum is discrete or continuous, the eigenfunctions can be normalized by setting the inner product of the eigenfunctions equal to either a Kronecker delta or a Dirac delta function, respectively.