Temas

Hola,
Me pueden ayudar con el siguiente código, no comprendo la función de int iK en esta FFT ya que los valores cuando me dan el resultado no son los imaginarios y reales que deberian ser entonces no se si estoy ejecutando mal el codigo o como es que deberia leerlo. Ademas debo hacerle la conjugada a los numeros ingresados en signal, esto para hacer la conjugada de la FFT (abs(fft)). Muchas Gracias de Ante Mano.

Código [Seleccionar] Expandir

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define M_PI 3.14159265358979323846264338327

void calcImag(double radians_signal[], double signal[], int k);
void calcReal(double radians_signal[], double signal[], int k);
double sum(double c[]);


double signal[] = {2.28025, 1.32888, 0.39326, -0.49619, -1.31121, -2.02672, -2.62174,
   -3.08015, -3.39124, -3.55077, -3.55763, -3.42069, -3.15151,
   -2.76733, -2.28963, -1.74326, -1.15541, -0.55456, 0.03068,
   0.57271, 1.04606, 1.42835, 1.7122, 1.85105, 1.86948, 1.75376,
   1.50688, 1.13742, 0.65924, 0.09094, -0.54489, -1.22254,
   -1.91419, -2.59102, -3.22433, -3.78672, -4.25312, -4.60188,
   -4.81556, -4.8817, -4.79336, -4.54939, -4.15456, -3.61943,
   -2.95996, -2.19702, -1.35554, -0.46368, 0.44824, 1.34888,
   2.20699, 2.99264, 3.6783, 4.23987, 4.65761, 4.91685, 5.00855,
   4.92967, 4.68323, 4.27822, 3.72929, 3.05615, 2.28286, 1.43692,
   0.54824, -0.35197, -1.23239, -2.06272, -2.81485, -3.46385,
   -3.9889, -4.37404, -4.60875, -4.68828, -4.61378, -4.39223,
   -4.03611, -3.56286, -2.99417, -2.3551, -1.67308, -0.97682,
   -0.29515, 0.3441, 0.91522, 1.3956, 1.76664, 2.01448, 2.13052,
   2.1118, 1.96104, 1.68661, 1.30214, 0.826, 0.28055, -0.3087,
   -0.91416, -1.50721, -2.05935, -2.54337, -2.93442, -3.21099,
   -3.35583, -3.35666, -3.20667, -2.90487, -2.45619, -1.87128,
   -1.16626, -0.36208, 0.51622, 1.44039, 2.38004, 3.30375,
   4.18023, 4.97949, 5.67398, 6.23957, 6.65652, 6.91015, 6.99145,
   6.89738, 6.631, 6.20138, 5.62319, 4.91623, 4.10463, 3.216};

// size of table
int iN = 128;
// harmonics
int iK = 4;

double imc[4][128];
double rec[4][128];

/*
*
*/
int main()
{
   double amplitude[4];
   double phase[4];
   double degreesSignal[128];
   double imcSum[4];
   double radiansSignal[128];
   double recSum[4];

   int i = 0;

   for (i = 0; i < iN; i++)
   {
       degreesSignal[i] = (360.0 / (double) iN) * (double) i;

       //printf("Degree Signal: %f \n", degreesSignal[i]);

       radiansSignal[i] = degreesSignal[i] * (M_PI / 180.0);

       //printf("Radians Signal: %f \n", radiansSignal[i]);
   }

   // get the real coefficients
   for (i = 0; i < iK; i++)
   {
       calcReal(radiansSignal, signal, i + 1);
   }

   // sum the real coefficients
   for (i = 0; i < iK; i++)
   {
       recSum[i] = sum(rec[i+1]);

       //printf("Real Sum: %f \n", recSum[i]);
   }

   // get the imag coefficients
   for (i = 0; i < iK; i++)
   {
       calcImag(radiansSignal, signal, i + 1);
   }

   // sum the imag coefficients
   for (i = 0; i < iK; i++)
   {
       imcSum[i] = sum(imc[i + 1]);

       //printf("Imaginary Sum: %f \n", recSum[i]);
   }

   // calculate amplitude (Fourier coefficients)
   // a[i] = 2(abs(RECSum[i]*abs(IMCSum[i])
   for (i = 0; i < iK; i++)
   {
       amplitude[i] = 2.0 * (sqrt(pow(recSum[i], 2.0) + pow(imcSum[i], 2.0)));

       //printf("Amplitude: %f \n", amplitude[i]);
   }

   // calculate phase
   // atan(abs(b/a))
   for (i = 0; i < iK; i++)
   {
       double temp = (sqrt(pow(imcSum[i], 2)
               / pow(recSum[i], 2)));
       phase[i] = atan(temp);
       
       //printf("Phase: %f \n", phase[i]);
   }

   for (i = 0; i < iK; i++)
   {
       printf("REC %d: %f\n", (i + 1), recSum[i]);
       printf("IMC  %d: %f\n", (i + 1), imcSum[i]);
       printf("Amplitude(K=%d): %f\n", (i + 1), amplitude[i]);
       printf("Phase(K=%d): %f\n", (i + 1), phase[i]);
       printf("Degrees(K=%d): %f\n", (i + 1), phase[i]*(180.0/M_PI));
       printf("\n");
   }

   return (EXIT_SUCCESS);
}

void calcImag(double radians_signal[], double signal[], int k)
{
   imc[k][0] = signal[0] * sin(-radians_signal[0]);

   for (int i = 1; i < iN; i++)
   {
       // for when the modular value is 0
       // prevents array out of bounds
       // IMC[array.length - 0]...
       // use the first sin value instead
       if ((i * k) % iN == 0)
       {
           imc[k][i] = signal[i] * sin(radians_signal[0]);
       }
       else
       {
           imc[k][i] = (signal[i] * sin(radians_signal[iN - (i * k) % iN]));
       }

       //printf("Imaginary Signal: %f \n", imc[k][i]);
   }
}

void calcReal(double radians_signal[], double signal[], int k)
{
   rec[k][0] = signal[0] * cos(radians_signal[0]);

   for (int i = 1; i < iN; i++)
   {
       // for when the modular value is 0
       // prevents array out of bounds
       // REC[array.length - 0]
       // use the first sin value instead
       if (((i * k) % iN) == 0)
       {
           rec[k][i] = signal[i] * cos(radians_signal[0]);
       }
       else
       {
           rec[k][i] = +(signal[i] * cos(radians_signal[iN - (i * k) % iN]));
       }

       //printf("REC: %d (n=%d) %f \n", k, i, rec[k][i]);
   }
}

double sum(double c[])
{
   double dCSum = 0;

   for (int i = 0; i < iN; i++)
   {
       dCSum += c[i];
   }

   dCSum = dCSum / iN;

   return dCSum;
}