How to derive Legendre Polynomials?

In summary, the method used to derive Legendre polynomials is by solving the Legendre equation using the method of power series. This involves substituting a power series into the equation and finding a recursive relation for the coefficients. The first three Legendre polynomials, P0(x) = 1, P1(x) = x, and P2(x) = 1/2 (3x2 - 1), can be derived using this method. Some students may only be given a table of Legendre polynomials in class, but understanding the method of derivation can provide a deeper understanding of these polynomials.
  • #1
terp.asessed
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Note that filling in the attempt at solution is mandatory.

Homework Statement


Could someone explain how Legendre polynomials are derived, particularly first three ones? I was only given the table in the class, not steps to solving them...so I am curious.

Homework Equations


P0(x) = 1
P1(x) = x
P2(x) = 1/2 (3x2 - 1)

The Attempt at a Solution


...
 
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  • #2
One way is solving the Legendre equation([itex]\frac{d}{dx} [(1-x^2) \frac{dP_n}{dx}]+n(n+1)P_n=0[/itex]) using the method of power series.(Substituting [itex] y=\sum_{n=0}^\infty a_n x^n [/itex] in the equation and finding a recursive relation for the coefficients.)
 
  • #3
Thanks! The equation was NEVER given in the class, so I was stuck with the table, but again thanks!
 

1. What are Legendre polynomials?

Legendre polynomials are a set of orthogonal polynomials that appear in many areas of mathematics and physics. They are named after French mathematician Adrien-Marie Legendre.

2. How are Legendre polynomials derived?

Legendre polynomials can be derived using various methods, such as the Rodrigues formula, Gram-Schmidt process, or the differential equation method. Each method involves a different approach and can lead to different forms of the polynomials.

3. What is the significance of Legendre polynomials?

Legendre polynomials have many applications in mathematics and physics, including solving differential equations, numerical integration, and spherical harmonics. They also have connections to other areas of mathematics, such as number theory and combinatorics.

4. Can you provide an example of a Legendre polynomial?

One example of a Legendre polynomial is P2(x) = (3x2 - 1)/2. This is a second-order polynomial that is orthogonal to all lower-order Legendre polynomials.

5. Are there any limitations to using Legendre polynomials?

While Legendre polynomials have many useful properties, they may not always be the most efficient or accurate method for solving certain problems. In some cases, other types of orthogonal polynomials, such as Chebyshev or Hermite polynomials, may be more suitable. It is important to consider the specific problem and determine the best approach for deriving the polynomials.

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