ights for Gauss-Hermite quadrature.
The sample points are the roots of the nth degree Hermite polynomial,
:math:`H_n(x)`. These sample points and weights correctly integrate
polynomials of degree :math:`2n - 1` or less over the interval
:math:`[-\infty, \infty]` with weight function :math:`f(x) = e^{-x^2}`.

This method relies on asymptotic expansions which work best for n > 150.
The algorithm has linear runtime making computation for very large n
feasible.

Parameters
----------
n : int
    quadrature order

Returns
-------
nodes : ndarray
    Quadrature nodes
weights : ndarray
    Quadrature weights

See Also
--------
roots_hermite

References
----------
.. [townsend.trogdon.olver-2014]
   Townsend, A. and Trogdon, T. and Olver, S. (2014)
   *Fast computation of Gauss quadrature nodes and
   weights on the whole real line*. :arXiv:`1410.5286`.

.. [townsend.trogdon.olver-2015]
   Townsend, A. and Trogdon, T. and Olver, S. (2015)
   *Fast computation of Gauss quadrature nodes and
   weights on the whole real line*.
   IMA Journal of Numerical Analysis
   :doi:`10.1093/imanum/drv002`.
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