                        /* Structure for Dobson/Fitch nonlinear filter */
typedef struct  {
        OPDS    h;
        MYFLT   *ar, *in, *a, *b, *d, *C, *L;   /* The parameter */
        AUXCH   delay;          /* Buffer for old values */
        int     point;          /* Pointer to old values */
} NLFILT;

