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/* -*- c++ -*- */
/*
* Copyright 2004,2007,2008,2012,2018 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifndef INCLUDED_FFT_FFT_VCC_H
#define INCLUDED_FFT_FFT_VCC_H
#include <gnuradio/fft/api.h>
#include <gnuradio/sync_block.h>
namespace gr {
namespace fft {
/*!
* \brief Compute forward or reverse FFT. complex vector in / complex vector out.
* \ingroup fourier_analysis_blk
*
* The FFT operation is defined for a vector \f$x\f$ with \f$N\f$ uniformly
* sampled points by
*
* \f[ X(a) = \sum_{k=0}^{N-1} x(a) \cdot e^{-j 2\pi k a / N} \f]
*
* \f$ X = FFT\{x\} \f$ is the the FFT transform of \f$x(a)\f$, \f$j\f$ is
* the imaginary unit, \f$k\f$ and \f$a\f$ range from \f$0\f$ to \f$N-1\f$.
*
* The IFFT operation is defined for a vector \f$y\f$ with \f$N\f$
* uniformly sampled points by
*
* \f[ Y(b) = \sum_{k=0}^{N-1} y(b) \cdot e^{j 2\pi k b / N} \f]
*
* \f$Y = IFFT\{y\}\f$ is the the inverse FFT transform of \f$y(b)\f$,
* \f$j\f$ is the imaginary unit, \f$k\f$ and \f$b\f$ range from \f$0\f$ to
* \f$N-1\f$.
*
* \b Note, that due to the underlying FFTW library, the output of a FFT
* followed by an IFFT (or the other way around) will be scaled i.e.
* \f$FFT\{ \, IFFT\{x\} \,\} = N \cdot x \neq x\f$.
*
* \see http://www.fftw.org/faq/section3.html#whyscaled
*/
class FFT_API fft_vcc : virtual public sync_block
{
public:
// gr::fft::fft_vcc::sptr
typedef boost::shared_ptr<fft_vcc> sptr;
/*! \brief
* \param[in] fft_size N.
* \param[in] forward True performs FFT, False performs IFFT.
* \param[in] window Window function to be used.
* \param[in] shift True moves DC carrier to the middle.
* \param[in] nthreads Number of underlying threads.
*/
static sptr make(int fft_size,
bool forward,
const std::vector<float>& window,
bool shift = false,
int nthreads = 1);
virtual void set_nthreads(int n) = 0;
virtual int nthreads() const = 0;
virtual bool set_window(const std::vector<float>& window) = 0;
};
} /* namespace fft */
} /* namespace gr */
#endif /* INCLUDED_FFT_FFT_VCC_H */
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