# Ordinary Differential Equations/Legendre Equation

In mathematics, **Legendre's differential equation** is

**Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle {d \over dx} \left[ (1-x^2) {d \over dx} P_n(x) \right] + n(n+1)P_n(x) = 0.}**

They are named after Adrien-Marie Legendre. This ordinary differential equation is frequently encountered in physics and other technical fields. In particular, it occurs when solving Laplace's equation (and related partial differential equations) in spherical coordinates.

The Legendre differential equation may be solved using the standard power series method. The equation has regular singular points at **Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): x=\pm 1**
so, in general, a series solution about the origin will only converge for . When *n* is an integer, the solution that is regular at is also regular at , and the series for this solution terminates (i.e. is a polynomial).

The solutions for **Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle n = 0, 1, 2 \dots }**
(with the normalization **Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle P_n\left(1\right)=1}**
) form a polynomial sequence of orthogonal polynomials called the **Legendre polynomials**. Each Legendre polynomial is an *n*th-degree polynomial. It may be expressed using Rodrigues' formula: