miniprojet/tests/examples/test-fft.cpp

#include <math.hpp>
#include <cmath>
#include <fstream>
#include <ctime>

void create_plot_file(std::string filename, const math::csignal& tfd) {
  std::ofstream data_file(filename + ".data");
  for (int i=0; i<tfd.size(); ++i) {
    data_file << tfd[i].real()
              << " "
              << tfd[i].imag()
              << std::endl;
  }
  data_file.close();
}

int main(int argc, char** argv) {
  math::csignal s;
  double fe = 6000;
  double f0 = 400;
  int n = 30;
  if (argc > 1) {
    n = atoi(argv[1]);
  }

  for (int i=0; i<100; ++i) {
    s.push_back(math::complex(std::sin(2*math::pi()*f0*float(i)/fe), 0));
  }

  std::cout << math::mean(s) << std::endl;

  math::csignal tfd;
  clock_t begin = std::clock();

  for (int i=0; i<n; ++i) {
    tfd = math::fft(s, 2000);
  }

  clock_t end = clock();
  std::cout << "Time to compute " << n << " fft: "<< double(end-begin) / CLOCKS_PER_SEC << std::endl;
  std::cout << "Average time: " << double(end-begin) / CLOCKS_PER_SEC / n << std::endl;

  math::csignal mod;
  for (int i=0; i<tfd.size(); ++i) {
    double R = tfd[i].real();
    double I = tfd[i].imag();
    double a = std::sqrt(R*R + I*I);
    mod.push_back(math::complex(float(i)/tfd.size()*fe, a));
  }
  create_plot_file("graph", mod);
  return 0;
}