/*! \file fftwaff.h
* \brief use fftw together with aff containers (prototypes)
*
* ----------------------------------------------------------------------------
*
* $Id$
* \author Thomas Forbriger
* \date 11/07/2006
*
* use fftw together with aff containers (prototypes)
*
* link with -lrfftw -lfftw -lm -laff
*
* ----
* libfourier is free software; 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.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
* ----
*
*
* Copyright (c) 2006 by Thomas Forbriger (BFO Schiltach)
*
* REVISIONS and CHANGES
* - 11/07/2006 V1.0 Thomas Forbriger
* - 12/09/2007 V1.1 first running version
* - 07/10/2010 V1.2
* - migrate to FFTW3:
* - use different fftw header file (fftw3.h)
* - type of FFTW plan has changed
* - 02/10/2012 V1.3
* - provide size calculation functions
*
* Migration to FFTW3:
* - The location of the arrays in memory are part of the plan.
* Consequently we have to either create a new plan for each transform or to
* allocate the working array together with the plan and keep it available in
* the background. The solution of choice is to keep arrays. We will
* introduce a control parameter to the arguments of the constructor which
* optionally allows to get rid of the arrays after each transformation.
* - FFTW3 uses wisdom by default.
* \code
* void fftw_forget_wisdom(void);
* \endcode
* should be called by the destructor of the class. Alternatively
* \code
* void fftw_cleanup(void);
* \endcode
* could be called which apparently is even more rigorous. Plans, however,
* must be destroyed prior to calling \c fftw_cleanup.
* - The FFTW documentation states:
* To the extent that this is true, if you have a variable
* \code
* complex *x,
* \endcode
* you can pass it directly to FFTW via
* \code
* reinterpret_cast(x).
* \endcode
*
* ============================================================================
*/
// include guard
#ifndef TF_FFTWAFF_H_VERSION
#define TF_FFTWAFF_H_VERSION \
"TF_FFTWAFF_H V1.3"
#define TF_FFTWAFF_H_CVSID \
"$Id$"
#include
#ifdef FFTWFALLBACK
#include
#else
#include
#endif
#include
namespace fourier {
/*! All Fourier transform stuff is collected here.
*/
namespace fft {
/*! A rigid class to do simple transforms using libdrfftw.a.
*
* uses real double arrays
*
* How to use this class:
*
* You may create one instance of this class and use it to transform
* several signals in both directions in turn. The class itself takes care
* of the transform size and creates a new plan if necessary. FFTs are
* invoked by the bracket operators. You should use the class object like
* a function. The scaling operators (taking the sampling interval as one
* of their arguments) return a series or spectrum scaled appropriately to
* match the values of samples from the corresponding Fourier integral
* transform (usual convention with \f$dt\f$ and \f$df\f$
* integrals - not \f$d \omega\f$).
*
* \note
* The appropriate number of samples for the time series obtained from a
* given set of Fourier coefficients is non-unique, if only the Fourier
* coefficients for positive frequencies are given, as is the case here.
* A time series with \f$2n\f$ samples and a time series with \f$2n+1\f$
* samples both will results in a set of \f$n+1\f$ Fourier coefficients.
* The method to determine the required number of time samples from the
* imaginary part of the Nyquist Fourier coefficients only works if the
* Nyquist coefficient (at least real part) is finite - which is not the
* case for most of our signals. This way we will obtain \f$n+1\f$ Fourier
* coefficients from \f$2n\f$ time series samples. When reconstructing the
* time series, we will obtain \f$2n+1\f$ samples with a sampling interval
* now being \f$2n/(2n+1)\f$ of the original interval. For this reason it
* is appropriate to set the size of the expected time series explicitely
* either by using the constructor
* DRFFTWAFF::DRFFTWAFF(const unsigned int& n) or by
* calling DRFFTWAFF::size(const unsigned int& s) prior to
* DRFFTWAFF::operator()(const Tspectrum::Tcoc& s).
*
* \sa \ref page_fftw3
*/
class DRFFTWAFF {
public:
typedef double Tsample;
typedef std::complex Tcoeff;
typedef aff::Series Tseries;
typedef aff::Series Tspectrum;
#ifdef FFTWFALLBACK
DRFFTWAFF(const unsigned int& n):
Msize(n), Mplan_forward(0), Mplan_backward(0) { }
DRFFTWAFF():
Msize(0), Mplan_forward(0), Mplan_backward(0) { }
#else
DRFFTWAFF(const unsigned int& n, const bool& deletearrays=false):
Msize(n), Mplan_forward(0), Mplan_backward(0),
Mseriesarray(0), Mspectrumarray(0),
Mdeletearrays(deletearrays) { }
DRFFTWAFF(const bool& deletearrays=false):
Msize(0), Mplan_forward(0), Mplan_backward(0),
Mseriesarray(0), Mspectrumarray(0),
Mdeletearrays(deletearrays) { }
#endif
~DRFFTWAFF();
Tspectrum operator()(const Tseries::Tcoc& s,
const bool& debug=false) const;
Tseries operator()(const Tspectrum::Tcoc& s,
const bool& debug=false) const;
Tspectrum operator()(const Tseries::Tcoc& s,
const Tsample& dt,
const bool& debug=false) const;
Tseries operator()(const Tspectrum::Tcoc& s,
const Tsample& dt,
const bool& debug=false) const;
Tsample scale_series(const Tsample& dt) const;
Tsample scale_spectrum(const Tsample& dt) const;
unsigned int size() const { return(Msize); }
void size(const unsigned int& s) const { this->set_size(s); }
//! return number of coefficients for given number of samples
inline
static unsigned int spectrumsize(const unsigned int& n)
{ return(n/2+1); }
//! return number of samples for given number of coefficients
inline
static unsigned int seriessize(const unsigned int& n)
{ return(n*2-1); }
private:
void create_plan_forward() const;
void create_plan_backward() const;
void delete_plans() const;
#ifndef FFTWFALLBACK
void create_arrays() const;
void delete_arrays() const;
unsigned int ssize() const
{ return(DRFFTWAFF::spectrumsize(this->size())); }
#endif
void set_size(const unsigned int& n) const;
mutable unsigned int Msize;
#ifdef FFTWFALLBACK
mutable rfftw_plan Mplan_forward;
mutable rfftw_plan Mplan_backward;
#else
mutable fftw_plan Mplan_forward;
mutable fftw_plan Mplan_backward;
mutable double *Mseriesarray;
mutable fftw_complex *Mspectrumarray;
mutable Tspectrum Mspectrum;
mutable Tseries Mseries;
bool Mdeletearrays;
#endif
}; // class DRFFTWAFF
} // namespace ftt
} // namespace fourier
#endif // TF_FFTWAFF_H_VERSION (includeguard)
/* ----- END OF fftwaff.h ----- */