// Function prototype for the initialization model; generates a sample pose from
// an appropriate distribution.
typedef pf_vector_t (*pf_init_model_fn_t) (void *init_data); // Function prototype for the action model; generates a sample pose from
// an appropriate distribution
typedef void (*pf_action_model_fn_t) (void *action_data, 
                                      struct _pf_sample_set_t* set);

// Function prototype for the sensor model; determines the probability
// for the given set of sample poses.
typedef double (*pf_sensor_model_fn_t) (void *sensor_data, 
                                        struct _pf_sample_set_t* set);

typedef pf_vector_t (*) (void *init_data) pf_init_model_fn_t;

typedef void (*) (void *action_data, struct _pf_sample_set_t* set) pf_action_model_fn_t;