/* Last edited on 2023-01-14 11:49:58 by stolfi */

    double quartic_win(int32_t z, int32_t N)
      { double r = (z + 0.5)/N;
        double w = 4*r*(1 - r);
        return w*w;
      }

typedef struct spectrum_table_entry_t 
  { double fmin;   /* Lower endpoint of range. */
    double fmax;   /* Upper endpoint of range. */
    double freq;   /* A middling value in range. */
    double nTerms; /* Number of Hartley terms in range. */
    double *power; /* Pointer to total power per channel. */
  } spectrum_table_entry_t;
  /* An entry of a spectrum table. All Hartley spectrum terms with 
    frequencies in {[fmin _ fmax]} are counted in {nTerms}, an the
    their total power per channel {c} is stored in {power[c]}. */
    
vec_typedef(spectrum_table_t,spectrum_table,spectrum_table_entry_t);

vec_typedef(spectrum_table_t,spectrum_table,spetrum_table-entry_t);