@staticmethod
def deriv(n, sig, alp, dg, dh1, dh2, dh3, _bin, nu):
    """The derivatives of the operator function at x=0"""
    dh1[0] = 0.5 * 1.0j * sig
    exp1 = -0.5
    dh2[0] = alp
    exp2 = -1
    dh3[0] = -2 * nu
    exp3 = -1
    for i in range(1, n):
        dh1[i] = dh1[i - 1] * exp1
        exp1 -= 1
        dh2[i] = dh2[i - 1] * exp2
        exp2 -= 1
        dh3[i] = -nu * dh3[i - 1] * exp3
        exp3 -= 1
    dg[0] = 1
    dg[1] = dh1[0] + dh2[0] + dh3[0]
    for i in range(1, n):
        dg[i + 1] = dh1[i] + dh2[i] + dh3[i]
        for j in range(i):
            dg[i + 1] += _bin[i, j] * (dh1[j] + dh2[j] + dh3[j]) * dg[i - j]
    return dg, dh1, dh2, dh3
