FFTW3 interface for MArrays
[Multidimensional Dynamic Arrays]

Classes

• class ltl::FourierTransform< T, N >

Files

• file fftw.h

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Detailed Description

Interface to call libfftw3 FFT routines on MArrays up to rank 3.

Interface to fftw3 FFT library. Currently, each call to one of the FFT methods causes a new plan to be generated. This is highly inefficient, but safe. It guarantees that pointers to the data strorage of MArray do not escape by being stored in a plan that might survive the MArray object.

All transforms leave the output array un-normalized. To normalize (divide by number of elements) call normalize().

   #include <ltl/fftw.h>

   // example of 1-dimensional FFT using fftw3 library:
   MArray<double, 1> in(size);
   MArray<std::complex<double>, 1> out(size);
   FourierTransform<double,1> FFT;

   in = 10.0 +
        20.0 * sin(indexPosDbl(in,1) / double(size) * 2.0 * M_PI * 3.0) +
        30.0 * cos(indexPosDbl(in,1) / double(size) * 2.0 * M_PI * 4.0);
   FFT.FFT_Real2Complex(in,out);
   FFT.normalize(out);
   out = merge(real(out * conj(out)) > 1e-9, out, 0);
   std::cout << out << std::endl;