def METHOD_NAME(self, ts, tangent_delta=None):
    n = len(ts)
    result = np.zeros((n, 3))
    o = self.omega
    for i, coeff in enumerate(self.coeffs):
        j = i // 2
        if i % 2 == 0:
            cost = - np.cos((j+1)*o*ts)[np.newaxis].T
            result = result + ((j+1)*o)**2 * coeff*cost
        else:
            sint = - np.sin((j+1)*o*ts)[np.newaxis].T
            result = result + ((j+1)*o)**2 * coeff*sint
    return result