def METHOD_NAME(self, t):
    """Calculates derivatives of the rotation angles."""
    s = self.sched(t)
    l = self.eigenval(t)
    I = self.integral_eigen(t)
    derI = l
    sp = self.sched_p(t)
    lp = self.eigenvalp(l, s, sp)
    nt = self.n(l, s)
    ntp = self.nder(l, s, lp, sp)
    ft = self.f(l, s)
    ftp = self.fp(l, s, lp, sp)
    gt = 1 + ft**2 + 2 * ft * np.cos(2 * I)
    # Terms of the final sum for the derivative of the theta
    x1 = ntp * np.sqrt(gt)
    y1 = 2 * ft * ftp
    y2 = 2 * ftp * np.cos(2 * I)
    y3 = -2 * ft * np.sin(2 * I) * (2 * derI)
    dgt = y1 + y2 + y3
    absu00 = nt * np.sqrt(gt)
    dabsu = x1 + nt / np.sqrt(gt) * (dgt) / 2.0
    darcos = 2.0 / np.sqrt(1 - absu00**2)
    dtheta = darcos * dabsu
    # Let's do the derivative of the phi,psi
    upf = 1 - l
    dpf = 1 + l - 2 * s
    tanI = np.tan(I)
    dtan = l / np.cos(I) ** 2
    dfrac_01 = 2 * (lp - sp + sp * l - s * lp) / upf**2
    dfrac_00 = -2 * (lp - sp + sp * l - s * lp) / dpf**2
    inside_arga = tanI * (upf / dpf)
    inside_argb = -tanI * (dpf / upf)
    dinside_arga = dtan * (upf / dpf) + tanI * dfrac_00
    darga = dinside_arga / (1 + inside_arga**2)
    dinside_argb = -dtan * (dpf / upf) - tanI * dfrac_01
    dargb = dinside_argb / (1 + inside_argb**2)
    dpsi = -darga + dargb
    dphi = -darga - dargb
    return dphi, dtheta, dpsi