www.pudn.com > lib.zip > goertzel.C

/* Goertzel's algorithm for the discrete Fourier transform */ 
 
#include  
 
#include "private.h" 
#include "complex.h" 
#include "goertzel.h" 
#include "myaudio.h" 
 
#define TWOPI (2.0 * M_PI) 
 
goertzel::goertzel(float f) 
  { v1 = v2 = v3 = 0.0; 
    float theta = TWOPI * (f / SAMPLERATE); 
    w = complex(cos(theta), -sin(theta)); 
    fac = 2.0 * w.re; 
  } 
 
void goertzel::insert(float x) 
  { v1 = v2; v2 = v3; 
    v3 = fac*v2 - v1 + x; 
  } 
 
complex goertzel::result() 
  { return complex(v3) - (w * complex(v2)); 
  }