What is Legendre: Definition and 224 Discussions

In physical science and mathematics, Legendre polynomials (named after Adrien-Marie Legendre, who discovered them in 1782) are a system of complete and orthogonal polynomials, with a vast number of mathematical properties, and numerous applications. They can be defined in many ways, and the various definitions highlight different aspects as well as suggest generalizations and connections to different mathematical structures and physical and numerical applications.
Closely related to the Legendre polynomials are associated Legendre polynomials, Legendre functions, Legendre functions of the second kind, and associated Legendre functions.

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  1. I

    Legendre polynomials formula

    There is a question where you should find a formula for P-n(0) using the Legendre polynomials: P-n(x)=1/(2^n*n!) d^n/dx^n(x^2-1)^n , n=0,1,2,3... I tried to derive seven times by only substituting the n until n=7,I did that because i wanted to find something that i can build my formula but i...
  2. L

    The Legendre Transform for Hamiltonians?

    I'm trying to implement and extend the work of Emmanuel Prados (http://www-sop.inria.fr/odyssee/research/prados-faugeras:04b/thesis.htm). I'm trying to follow how Appendix A, "How to transform a convex Hamiltonian into a HJB Hamiltonian; Legendre Transform", works for the provided example. I've...
  3. N

    Legendre polynomial integration

    Homework Statement int x^m*P_n(x) dx=0 where integration is from (-1) to (+1).Given m<n Homework Equations The Attempt at a Solution I took integrand F(x) and saw that F(-x)=(-1)^(m+n)*F(x) should that help anyway?
  4. N

    How to Prove Properties of Legendre Polynomials?

    Homework Statement I am to prove that P_n(-x)=(-1)^n*P_n(x) And, P'_n(-x)=(-1)^(n+1)*P'_n(x) Homework Equations The Attempt at a Solution I know that whether a Legendre Polynomial is an even or odd function depends on its degree.It follows directly from the solution of...
  5. B

    Contour Integration with Legendre Functions

    Homework Statement P_n (z) and Q_n (z) are Legendre functions of the first and second kinds, respectively. The function f is a polynomial in z. Show that Q_n (z) = \frac{1}{2} P_n (z) \ln \left(\frac{z+1}{z-1} \right) + f_{n-1} (z) implies Q_n (z) = \frac{1}{2} \int \frac{P_n (t) \...
  6. A

    Struggling with Legendre Polynomials: Any Suggestions?

    Hello everyone i had some questions about legendre polynomials. I have solved most of them but i had just two not answered question. I tried to solve this problem by rodriguez rule but it was really hard for me. Could anyone help me or give me some hints for this question...
  7. A

    Legendre polynomials proof question.Help

    Hello everyone i had some questions about legendre polynomials. I have solved most of them but i had just two not answered question. I tried to solve this problem by rodriguez rule but it was really hard for me. Could anyone help me or give me some hints for this question...
  8. A

    Legendre poynomials proof question.Help

    Hello everyone i had some questions about legendre polynomials. I have solved most of them but i had just two not answered question. I tried to solve this problem by rodriguez rule but it was really hard for me. Could anyone help me or give me some hints for this question...
  9. S

    Proving Orthogonality of Legendre Polynomials P3 and P1

    To show that two Legendre polynomials(Pn and Pm) are orthogonal wht is the test that i have to use? is it this? \int_{-1}^{1} P_{n}(x)P_{m}(x) dx = 0 in that case to prove that P3 and P1 are orthogonal i have to use the above formula??
  10. L

    Expand a function in terms of Legendre polynomials

    Problem: Suppose we wish to expand a function defined on the interval (a,b) in terms of Legendre polynomials. Show that the transformation u = (2x-a-b)/(b-a) maps the function onto the interval (-1,1). How do I even start working with this? I haven't got a clue...
  11. L

    Proving Orthogonality of Legendre Polynomials

    Problem: Show that \int_{-1}^{1} x P_n(x) P_m(x) dx = \frac{2(n+1)}{(2n+1)(2n+3)}\delta_{m,n+1} + \frac{2n}{(2n+1)(2n-1)}\delta_{m,n-1} I guess I should use orthogonality with the Legendre polynomials, but if I integrate by parts to get rid of the x my integral equals zero. Any tip on...
  12. G

    Solution of hydrogen atom : legendre polynomials

    I was messing around with the \theta equation of hydrogen atom. OK, the equation is a Legendre differential equation, which has solutions of Legendre polynomials. I haven't studied them before, so I decided to take closed look and began working on the most simple type of Legendre DE. And the...
  13. G

    Legendre Polynomials Orthogonality Relation

    ...and orthogonality relation. The book says \int_{-1}^{1} P_n(x) P_m(x) dx = \delta_{mn} \frac{2}{2n+1} So I sat and tried derieving it. First, I gather an inventory that might be useful: (1-x^2)P_n''(x) - 2xP_n'(x) + n(n+1) = 0 [(1-x^2)P_n'(x)]' = -n(n+1)P_n(x) P_n(-x) = (-1)^n P_n(x)...
  14. E

    How is the Legendre transform defined in cases where g(p) equals 0?

    Legendre transform... If we define a function f(r) with r=x,y,z,... and its Legnedre transform g(p) with p=p_x ,p_y,p_z,... then we would have the equality: Df(r)=(Dg(p))^{-1} (1) where D is a differential operator..the problem is..what happens when g(p)=0?...(this problem is...
  15. R

    Legendre polynomials application

    I need some help. I fitted a 7th order legendre polynomial and got the L0 to L7 coefficients for different ANOVA classes. How can I get a back transformation in order to plot each class using the estimated coefficients? Thanks to anybody. Roberto.
  16. W

    Back Transformation for Legendre Polynomials

    some body who can explain for me the Legndre polynomials:eek: :eek:
  17. M

    Proof of orthogonality of associated Legendre polynomial

    Hi, I'm trying to prove the orthogonality of associated Legendre polynomial which is called to "be easily proved": Let P_l^m(x) = (-1)^m(1-x^2)^{m/2} \frac{d^m} {dx^m} P_l(x) = \frac{(-1)^m}{2^l l!} (1-x^2)^{m/2} \frac {d^{l+m}} {dx^{l+m}} (x^2-1)^l And prove \int_{-1}^1...
  18. A

    Is the legendre equation an example of a frobenius equation?

    is the legendre equation an example of a frobenius equation?
  19. A

    Legendre Polynomial: Understanding the Basics

    can someone explain step-by-step why the legendre polynomial came into being? I'm having one hard time understanding it...
  20. T

    Find Legendre Polynomials of Order 15+

    Hey there, does anyone know where I could find a list of Legendre Polynomials? I need them of the order 15 and above, and I haven't been able to find them on the net. Thanks!
  21. H

    Legendre Polynomial solutions

    Hi, I have a problem where I am given the Legendre equation and have been told 1 solution is u(x). It asks me to obtain an expression for the second solution v(x) corresponding to the same value of l. I think it requires Sturm Liouville treatment but don't have a clue how to begin. Please HELP!
  22. A

    Legendre equation and angular momentum

    Hi all, I've been doing a math problem about the Legendre differential equation, and finding there are two linearly independent solutions. When I was taught about quantum mechanics the polynomial solutions were introduced to me as the basis for spherical harmonics and consequently the...
  23. A

    Legendre symbol proof for (-5/p)

    I am working on some homework that I already handed in, but I can't get one of the problems. The fourth problem on the HW was to prove the forms of (-1/p), (2/p), (3/p), (-5/p), and (7/p). I did this for -1 and 2 using the quadratic residues and generalizing a form for them. for 3 and 7 i...
  24. T

    Legendre Polynomials: Beginner's Guide

    hi folks! I have been trying to figure out some plausible geometric intrepretation to legendre polynomials and what are they meant to do. I have come across the concept of orthogonal polynomials while working with some boundary value problems in solid mechanics and wasn't able to come to...
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