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Gauss-Hermite Quadrature Nodes & Weights

Enter the order n to list the Gauss-Hermite quadrature nodes (roots of the Hermite polynomial Hₙ) and weights for the weight function e^(-x²) in a table.

Input

Enter the order n to compute the nodes and weights of Gauss-Hermite quadrature (weight function e^(-x²)). Use them in the form ∫ f(x) e^(-x²) dx ≈ Σ wᵢ f(xᵢ), with e^(-x²) excluded from f(x).

An integer from 1 to 128, equal to the number of nodes.

Result

Order n

5

The roots of the Hermite polynomial Hₙ are used as nodes

Number of nodes

5

Sum of weights

1.7724538509

Weight function

e^(-x²)

Nodes and weights

Nodes xᵢ are in ascending order. The weights sum to the theoretical value √π ≈ 1.7724539.

#Node xᵢWeight wᵢ
1-0.95857246460.3936193232
2-2.02018287050.0199532421
300.9453087205
42.02018287050.0199532421
50.95857246460.3936193232

How it works

  • Gauss-Hermite quadrature approximates integrals over the whole real line with the weight e^(-x²): ∫_{-∞}^{∞} f(x) e^(-x²) dx ≈ Σ wᵢ f(xᵢ).
  • The nodes xᵢ are the roots of the (physicists') Hermite polynomial Hₙ(x) of order n, found here by Newton's method.
  • The weights are wᵢ = 2^(n-1)·n!·√π / (n²·Hₙ₋₁(xᵢ)²), computed in the log domain to avoid factorial overflow.
  • Nodes and weights are symmetric about the origin. The weights sum to √π ≈ 1.7724539, which serves as an accuracy check.
  • An order-n rule integrates polynomials f(x) of degree up to 2n−1 exactly.

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