testfft.cpp

用于进行一维和二维的傅利叶变换及其逆变换

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

#include "FFT.h"

const int len = 8192;
const int tests = 200;

main()
{
  int t0, t1;

  float *in = new float[len];
  float *outr = new float[len];
  float *outi = new float[len];
  float *outr2 = new float[len];
  float *outi2 = new float[len];
  float *outs = new float[len];

  for(int x=0; x<len; x++) {
	in[x] = sin(x/(float)len) + 1.3*cos(x/(float)len);
  }

  // Warm it up
  FFT(len, 0, in, NULL, outr, outi);
  RealFFT(len, in, outr2, outi2);
  PowerSpectrum(len, in, outs);

  printf("Testing FFT(%d):\n\n", len);

  int i;

  t0 = clock();
  for(i=0; i<tests; i++) {
	FFT(len, 0, in, NULL, outr, outi);
  }
  t1 = clock();

  printf("Complex FFT Time: %d us\n", int((t1-(double)t0)/tests+0.5));

  t0 = clock();
  for(i=0; i<tests; i++) {
	RealFFT(len, in, outr2, outi2);
  }
  t1 = clock();

  printf("Real FFT Time:  %d us\n", int((t1-(double)t0)/tests+0.5));

  t0 = clock();
  for(i=0; i<tests; i++) {
	PowerSpectrum(len, in, outs);
  }
  t1 = clock();

  printf("Spectrum Time:  %d us\n", int((t1-(double)t0)/tests+0.5));

  printf("\n");
  printf("Accuracy:\n");
  printf("\n");
  printf("     n   FFT            RealFFT         PowerSpectrum\n");

  for(i=0; i<len/2; i++) {
	printf("%6d:  %10e   %10e    %10e\n",
		   i,
		   outr[i]*outr[i] + outi[i]*outi[i],
		   outr2[i]*outr2[i] + outi2[i]*outi2[i],
		   outs[i]);
  }
}