started real optimization, added benchmark for FFT

bench/benchFFT.cpp

@@ -0,0 +1,64 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra. Eigen itself is part of the KDE project.
+//
+// Copyright (C) 2009 Mark Borgerding mark a borgerding net
+//
+// Eigen is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 3 of the License, or (at your option) any later version.
+//
+// Alternatively, you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of
+// the License, or (at your option) any later version.
+//
+// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License and a copy of the GNU General Public License along with
+// Eigen. If not, see <http://www.gnu.org/licenses/>.
+
+#include <complex>
+#include <vector>
+#include <Eigen/Core>
+#include <bench/BenchTimer.h>
+#include <unsupported/Eigen/FFT.h>
+
+using namespace Eigen;
+using namespace std;
+
+#ifndef NFFT
+#define NFFT 1024
+#endif
+
+#ifndef TYPE
+#define TYPE float
+#endif
+
+#ifndef NITS 
+#define NITS (10000000/NFFT)
+#endif
+
+int main() 
+{
+  vector<complex<TYPE> > inbuf(NFFT);
+  vector<complex<TYPE> > outbuf(NFFT);
+  Eigen::FFT<TYPE> fft;
+
+  fft.fwd( outbuf , inbuf);
+
+  BenchTimer timer;
+  timer.reset();
+  for (int k=0;k<8;++k) {
+      timer.start();
+      for(int i = 0; i < NITS; i++)
+          fft.fwd( outbuf , inbuf);
+      timer.stop();
+  }
+  double mflops = 5.*NFFT*log2((double)NFFT) / (1e6 * timer.value() / (double)NITS );
+  cout << "NFFT=" << NFFT << "  " << (double(1e-6*NFFT*NITS)/timer.value()) << " MS/s  " << mflops << "MFLOPS\n";
+}