typedef struct {
  int sweep_num;      /* Integer sweep number. */
  float elev;         /* Elevation angle (mean) for the sweep. */
  float beam_width;   /* This is in the ray header too. */
  float vert_half_bw; /* Vertical beam width divided by 2 */
  float horz_half_bw; /* Horizontal beam width divided by 2 */
  int nrays;
  float (*f)(Range x); /* Data conversion function. f(x). */
  Range (*invf)(float x); /* Data conversion function. invf(x). */ 
} Sweep_header;