benchFFT.cpp

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Mark Borgerding mark a borgerding net
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include <iostream>

#include <bench/BenchUtil.h>
#include <complex>
#include <vector>
#include <Eigen/Core>

#include <unsupported/Eigen/FFT>

using namespace Eigen;
using namespace std;

template <typename T>
string nameof();

template <>
string nameof<float>() {
  return "float";
}
template <>
string nameof<double>() {
  return "double";
}
template <>
string nameof<long double>() {
  return "long double";
}

#ifndef TYPE
#define TYPE float
#endif

#ifndef NFFT
#define NFFT 1024
#endif
#ifndef NDATA
#define NDATA 1000000
#endif

using namespace Eigen;

template <typename T>
void bench(int nfft, bool fwd, bool unscaled = false, bool halfspec = false) {
  typedef typename NumTraits<T>::Real Scalar;
  typedef typename std::complex<Scalar> Complex;
  int nits = NDATA / nfft;
  vector<T> inbuf(nfft);
  vector<Complex> outbuf(nfft);
  FFT<Scalar> fft;

  if (unscaled) {
    fft.SetFlag(fft.Unscaled);
    cout << "unscaled ";
  }
  if (halfspec) {
    fft.SetFlag(fft.HalfSpectrum);
    cout << "halfspec ";
  }

  std::fill(inbuf.begin(), inbuf.end(), 0);
  fft.fwd(outbuf, inbuf);

  BenchTimer timer;
  timer.reset();
  for (int k = 0; k < 8; ++k) {
    timer.start();
    if (fwd)
      for (int i = 0; i < nits; i++) fft.fwd(outbuf, inbuf);
    else
      for (int i = 0; i < nits; i++) fft.inv(inbuf, outbuf);
    timer.stop();
  }

  cout << nameof<Scalar>() << " ";
  double mflops = 5. * nfft * log2((double)nfft) / (1e6 * timer.value() / (double)nits);
  if (NumTraits<T>::IsComplex) {
    cout << "complex";
  } else {
    cout << "real   ";
    mflops /= 2;
  }

  if (fwd)
    cout << " fwd";
  else
    cout << " inv";

  cout << " NFFT=" << nfft << "  " << (double(1e-6 * nfft * nits) / timer.value()) << " MS/s  " << mflops << "MFLOPS\n";
}

int main(int argc, char** argv) {
  bench<complex<float> >(NFFT, true);
  bench<complex<float> >(NFFT, false);
  bench<float>(NFFT, true);
  bench<float>(NFFT, false);
  bench<float>(NFFT, false, true);
  bench<float>(NFFT, false, true, true);

  bench<complex<double> >(NFFT, true);
  bench<complex<double> >(NFFT, false);
  bench<double>(NFFT, true);
  bench<double>(NFFT, false);
  bench<complex<long double> >(NFFT, true);
  bench<complex<long double> >(NFFT, false);
  bench<long double>(NFFT, true);
  bench<long double>(NFFT, false);
  return 0;
}