def _hermite_param(ctx, n, z, parabolic_cylinder):
    """
    Combined calculation of the Hermite polynomial H_n(z) (and its
    generalization to complex n) and the parabolic cylinder
    function D.
    """
    n, ntyp = ctx._convert_param(n)
    z = ctx.convert(z)
    q = -ctx.mpq_1_2
    # For re(z) > 0, 2F0 -- http://functions.wolfram.com/
    #     HypergeometricFunctions/HermiteHGeneral/06/02/0009/
    # Otherwise, there is a reflection formula
    # 2F0 + http://functions.wolfram.com/HypergeometricFunctions/
    #           HermiteHGeneral/16/01/01/0006/
    #
    # TODO:
    # An alternative would be to use
    # http://functions.wolfram.com/HypergeometricFunctions/
    #     HermiteHGeneral/06/02/0006/
    #
    # Also, the 1F1 expansion
    # http://functions.wolfram.com/HypergeometricFunctions/
    #     HermiteHGeneral/26/01/02/0001/
    # should probably be used for tiny z
    if not z:
        T1 = [2, ctx.pi], [n, 0.5], [], [q*(n-1)], [], [], 0
        if parabolic_cylinder:
            T1[1][0] += q*n
        return T1,
    can_use_2f0 = ctx.isnpint(-n) or ctx.re(z) > 0 or \
        (ctx.re(z) == 0 and ctx.im(z) > 0)
    expprec = ctx.prec*4 + 20
    if parabolic_cylinder:
        u = ctx.fmul(ctx.fmul(z,z,prec=expprec), -0.25, exact=True)
        w = ctx.fmul(z, ctx.sqrt(0.5,prec=expprec), prec=expprec)
    else:
        w = z
    w2 = ctx.fmul(w, w, prec=expprec)
    rw2 = ctx.fdiv(1, w2, prec=expprec)
    nrw2 = ctx.fneg(rw2, exact=True)
    nw = ctx.fneg(w, exact=True)
    if can_use_2f0:
        T1 = [2, w], [n, n], [], [], [q*n, q*(n-1)], [], nrw2
        terms = [T1]
    else:
        T1 = [2, nw], [n, n], [], [], [q*n, q*(n-1)], [], nrw2
        T2 = [2, ctx.pi, nw], [n+2, 0.5, 1], [], [q*n], [q*(n-1)], [1-q], w2
        terms = [T1,T2]
    # Multiply by prefactor for D_n
    if parabolic_cylinder:
        expu = ctx.exp(u)
        for i in range(len(terms)):
            terms[i][1][0] += q*n
            terms[i][0].append(expu)
            terms[i][1].append(1)
    return tuple(terms)
dataset/ETHPy150Open fredrik-johansson/mpmath/mpmath/functions/orthogonal.py/_hermite_param/original