Laguerre Polynomial Calculator

L_n(x) on [0,∞)

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About Laguerre Polynomial Calculator

A Laguerre polynomial calculator computing L_n(x) via recurrence (n+1)L_{n+1}=(2n+1-x)L_n−nL_{n-1}. L_0=1, L_1=1−x, L_2=(x²−4x+2)/2. Hydrogen radial wavefunctions use associated Laguerre L_n^α. Client-side.

Laguerre Polynomial Calculator Features

  • L_n(x) value
  • Associated L_n^α
  • Coefficients
  • Hydrogen atom
  • Sequence
Laguerre polynomials: L_n(x) orthogonal on [0,∞) with weight e^{-x}. L_0=1, L_1=1−x, L_2=(x²−4x+2)/2. Recurrence: (n+1)L_{n+1}=(2n+1−x)L_n−nL_{n-1}. Rodrigues: L_n=(e^x/n!)d^n/dx^n(x^ne^{-x}).

How to Use

Enter n and x:

  • L_n(x): Evaluation
  • Sequence: L_0..L_n
  • Coefficients: Polynomial form

Hydrogen Atom

Radial wavefunction R_{nl}(r) ∝ L_{n-l-1}^{2l+1}(2r/na₀)·e^{-r/na₀}·(2r/na₀)^l. The associated Laguerre L_n^α determines the radial probability distribution. n−l−1 radial nodes.

Gauss-Laguerre

Zeros of L_n are nodes for Gauss-Laguerre quadrature: ∫_0^∞ e^{-x}f(x)dx ≈ Σw_if(x_i). Essential for integrals over [0,∞) with exponential decay. Exact for polynomials up to degree 2n-1.

Step-by-Step Instructions

  1. 1Enter degree n.
  2. 2Enter x value.
  3. 3Compute L_n(x).
  4. 4View sequence.
  5. 5See hydrogen.

Laguerre Polynomial Calculator — Frequently Asked Questions

What are associated Laguerre polynomials?+

L_n^α(x) = (-1)^α d^α/dx^α L_{n+α}(x). For α=0, these are ordinary Laguerre. For the hydrogen atom, α=2l+1 where l is the angular quantum number. They're orthogonal with weight x^α·e^{-x}.

Why do they appear in quantum mechanics?+

The radial Schrödinger equation for hydrogen, after substitution, becomes Laguerre's equation. The quantization condition (bound states) selects polynomial solutions = Laguerre polynomials. The quantum numbers n,l directly index these polynomials.

How do Laguerre polynomials relate to exponentials?+

L_n(x) = Σ_{k=0}^n C(n,k)(-x)^k/k!. This is a truncated Taylor series of e^{-x} scaled by binomial coefficients. As n→∞, L_n(x/n)→J_0(2√x), a Bessel function.

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