def h_eval(C, n, x):
    """
    Evaluate h_n(x), the n-th normalized hermite polynomial.  It is assumed
    that the coefficients have already been multiplied by sqrt(n!) to make the
    polynomials orthonormal.
    """
    xpow = 1.0
    sm = C[n, 0]
    for i in range(1, n+1):
        xpow = xpow * x
        sm += C[n, i] * xpow
    return sm