Derivation for Rodrigues formula (orthogonal polynomials)

Legendre differential equation. In summary, the family of orthogonal polynomials under a weight w(x) can be described by a differential equation and an inner product, and the general form of the Rodrigues formula was likely derived from specific examples such as the Legendre polynomials.
  • #1
J Hill
12
0
Okay, so given a family of orthogonal polynomials under a weight w(x) is described by the differential equation

[itex]Q(x) f'' + L(x) f' + \lambda f [/itex] = 0, where Q(x) is a quadratic (at most) and L(x) is linear (at most).

with the inner product

[itex]\langle f | g \rangle \equiv \int_X f^*(x) g(x) w(x) dx [/itex], it is known that

[itex]f_n(x) = \frac{a_n}{w(x)} \frac{d^n}{dx^n} \Big ( Q^n(x) w(x) \Big) [/itex]

Now, I was hoping that someone might be familiar with the derivation of this general form of the Rodrigues formula-- or is it the case that it was just generalized from more specific examples (such as the Legendre polynomials, etc.)?
 
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  • #2

What is the derivation for Rodrigues formula?

The derivation for Rodrigues formula is a mathematical process used to derive a formula for orthogonal polynomials. It involves using the Gram-Schmidt process to generate a set of orthogonal polynomials from a given set of polynomials.

What is the significance of Rodrigues formula?

Rodrigues formula is significant because it provides a way to express orthogonal polynomials in terms of a simple recurrence relation. This makes it easier to compute the coefficients of the polynomials and perform other calculations.

How is Rodrigues formula related to the Gram-Schmidt process?

Rodrigues formula is closely related to the Gram-Schmidt process, as it uses the process to generate a set of orthogonal polynomials. The process involves orthogonalizing a set of polynomials by subtracting off their projections onto the previously generated orthogonal polynomials.

What are some applications of Rodrigues formula?

Rodrigues formula has many applications in various fields of mathematics and physics. It is used in numerical analysis, approximation theory, and differential equations. It is also used in quantum mechanics to solve the Schrodinger equation and to find the energy levels of particles in a potential well.

Is Rodrigues formula limited to a specific type of polynomial?

No, Rodrigues formula can be used to derive orthogonal polynomials for any set of polynomials, as long as they satisfy certain conditions. These conditions include being mutually orthogonal and having a finite inner product space.

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