cdef class KF1D: cdef public: double x0_0 double x1_0 double K0_0 double K1_0 double A0_0 double A0_1 double A1_0 double A1_1 double C0_0 double C0_1 double A_K_0 double A_K_1 double A_K_2 double A_K_3