Hermite Polynomial Calculator

H_n(x) = (-1)^n e^{x²} d^n/dx^n e^{-x²}

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About Hermite Polynomial Calculator

A Hermite polynomial calculator computing (physicist's) H_n(x) via recurrence H_{n+1}=2xH_n−2nH_{n-1}. H_0=1, H_1=2x, H_2=4x²−2, H_3=8x³−12x. Quantum harmonic oscillator wavefunctions ψ_n ∝ H_n(x)e^{-x²/2}. Client-side.

Hermite Polynomial Calculator Features

  • H_n(x) value
  • Probabilist He_n
  • Coefficients
  • QHO connection
  • Sequence
Hermite polynomials: H_n(x) orthogonal with weight e^{-x²}. Physicist: H_0=1, H_1=2x, H_2=4x²−2. Probabilist: He_n(x)=2^{-n/2}H_n(x/√2). Quantum harmonic oscillator: ψ_n(x) = (1/√(2^n·n!·√π))H_n(x)e^{-x²/2}.

How to Use

Enter n and x:

  • H_n(x): Physicist convention
  • He_n(x): Probabilist
  • Sequence: Step values

Quantum Mechanics

The quantum harmonic oscillator has energy levels E_n=(n+½)ℏω. The wavefunctions are ψ_n(x)∝H_n(αx)exp(-α²x²/2) where α=√(mω/ℏ). The n-th excited state has n nodes (zeros).

Two Conventions

Physicist: H_n, weight e^{-x²}, H_n(0)=(-1)^{n/2}·n!/(n/2)! for even n. Probabilist: He_n, weight e^{-x²/2}, monic. Relation: H_n(x)=2^{n/2}He_n(x√2). Always check which convention!

Step-by-Step Instructions

  1. 1Enter degree n.
  2. 2Enter x value.
  3. 3Compute H_n(x).
  4. 4See probabilist.
  5. 5View QHO wavefunction.

Hermite Polynomial Calculator — Frequently Asked Questions

Why two conventions?+

Physicists use weight e^{-x²} (matches QHO potential). Probabilists use e^{-x²/2} (matches normal distribution). Both are valid orthogonal systems. The physicists' H_n has leading coefficient 2^n; probabilists' He_n is monic.

How do Hermite polynomials connect to the normal distribution?+

He_n(x) are the 'natural' polynomials for the Gaussian. The Hermite expansion: f(x) = Σ a_n·He_n(x)·φ(x) where φ is the standard normal PDF. This is the Gram-Charlier expansion used in statistics and finance.

What about Gauss-Hermite quadrature?+

Zeros of H_n are nodes for Gauss-Hermite quadrature: ∫e^{-x²}f(x)dx ≈ Σw_if(x_i). Exact for polynomials up to degree 2n-1. Essential for integrating functions against Gaussian weights.

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