Lookup table class for Fast Fourier Transformation. More...

#include <GFftWavetable.hpp>

Inheritance diagram for GFftWavetable:

Public Member Functions
	GFftWavetable (void)
	Void constructor. More...

	GFftWavetable (const int &size)
	Wave table constructor. More...

	GFftWavetable (const GFftWavetable &wavetable)
	Copy constructor. More...

virtual	~GFftWavetable (void)
	Destructor. More...

GFftWavetable &	operator= (const GFftWavetable &wavetable)
	Assignment operator. More...

std::complex< double > &	operator[] (const int &index)
	Return reference to trigonometric coefficient. More...

const std::complex< double > &	operator[] (const int &index) const
	Return reference to trigonometric coefficient (const version) More...

void	clear (void)
	Clear lookup table for Fast Fourier Transform. More...

GFftWavetable *	clone (void) const
	Clone lookup table for Fast Fourier Transform. More...

std::string	classname (void) const
	Return class name. More...

int	size (void) const
	Return number of trigonometric coefficients. More...

const int &	index (const int &factor) const
	Return start index for a given factor. More...

int	factors (void) const
	Return number of factorisation factors. More...

int	factor (const int &index) const
	Return factorisation factor. More...

std::string	print (const GChatter &chatter=NORMAL) const
	Print lookup table for Fast Fourier Transform information. More...

Public Member Functions inherited from GBase
virtual	~GBase (void)
	Destructor. More...

Protected Member Functions
void	init_members (void)
	Initialise class members. More...

void	copy_members (const GFftWavetable &wavetable)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

void	set_members (const int &n)
	Set wavetable. More...

void	set_factors (const int &n)
	Compute FFT factorisation. More...

Protected Attributes
std::vector< int >	m_factors
	Wavetable factors. More...

std::vector< int >	m_twiddle
	Start index of factors. More...

std::vector< std::complex < double > >	m_trig
	Trigonometric coefficients. More...

Detailed Description

Lookup table class for Fast Fourier Transformation.

Definition at line 44 of file GFftWavetable.hpp.

Constructor & Destructor Documentation

GFftWavetable::GFftWavetable ( void )

Void constructor.

Definition at line 52 of file GFftWavetable.cpp.

References init_members().

Referenced by clone().

GFftWavetable::GFftWavetable ( const int & size )

explicit

Wave table constructor.

Parameters

[in] size Array size.

Constructs the lookup table for Fast Fourier Transformation for a given array size.

Definition at line 70 of file GFftWavetable.cpp.

References init_members(), and set_members().

GFftWavetable::GFftWavetable ( const GFftWavetable & wavetable )

Copy constructor.

Parameters

[in] wavetable Lookup table for Fast Fourier Transform.

Definition at line 88 of file GFftWavetable.cpp.

References copy_members(), and init_members().

GFftWavetable::~GFftWavetable ( void )

virtual

Destructor.

Definition at line 104 of file GFftWavetable.cpp.

References free_members().

Member Function Documentation

std::string GFftWavetable::classname ( void ) const

inlinevirtual

Return class name.

Returns: String containing the class name ("GFftWavetable").

Implements GBase.

Definition at line 89 of file GFftWavetable.hpp.

void GFftWavetable::clear ( void )

virtual

Clear lookup table for Fast Fourier Transform.

Implements GBase.

Definition at line 156 of file GFftWavetable.cpp.

References free_members(), and init_members().

GFftWavetable * GFftWavetable::clone ( void ) const

virtual

Clone lookup table for Fast Fourier Transform.

Returns: Pointer to deep copy of lookup table for Fast Fourier Transform.

Implements GBase.

Definition at line 174 of file GFftWavetable.cpp.

References GFftWavetable().

void GFftWavetable::copy_members ( const GFftWavetable & wavetable )

protected

Copy class members.

Parameters

[in] wavetable Lookup table for Fast Fourier Transform.

Definition at line 272 of file GFftWavetable.cpp.

References m_factors, m_trig, and m_twiddle.

Referenced by GFftWavetable(), and operator=().

int GFftWavetable::factor ( const int & index ) const

Return factorisation factor.

Parameters

[in] index Factorisation index [0,...,factors()-1].

Returns: Factorisation factor.

Exceptions

GException::out_of_range Index is outside valid range.

Returns factorisation factor.

Definition at line 192 of file GFftWavetable.cpp.

References factors(), G_FACTOR, and m_factors.

Referenced by print(), set_factors(), and GFft::transform().

int GFftWavetable::factors ( void ) const

inline

Return number of factorisation factors.

Returns: Number of factorisation factors.

Definition at line 158 of file GFftWavetable.hpp.

References m_factors.

Referenced by factor(), print(), and GFft::transform().

void GFftWavetable::free_members ( void )

protected

Delete class members.

Definition at line 287 of file GFftWavetable.cpp.

Referenced by clear(), operator=(), and ~GFftWavetable().

const int & GFftWavetable::index ( const int & factor ) const

inline

Return start index for a given factor.

Parameters

[in] factor Factor index [0,...,factors()-1].

Returns the index of the first trigonometric coefficient for a given factor.

Definition at line 134 of file GFftWavetable.hpp.

References m_twiddle.

Referenced by GFft::transform().

void GFftWavetable::init_members ( void )

protected

Initialise class members.

Definition at line 255 of file GFftWavetable.cpp.

References m_factors, m_trig, and m_twiddle.

Referenced by clear(), GFftWavetable(), operator=(), and set_members().

GFftWavetable & GFftWavetable::operator= ( const GFftWavetable & wavetable )

Assignment operator.

Parameters

[in] wavetable Lookup table for Fast Fourier Transform.

Returns: Lookup table for Fast Fourier Transform.

Definition at line 126 of file GFftWavetable.cpp.

References copy_members(), free_members(), and init_members().

std::complex< double > & GFftWavetable::operator[] ( const int & index )

inline

Return reference to trigonometric coefficient.

Parameters

[in] index Trigonometric coefficient index [0,...,size()-1].

Returns a reference to the trigonometric coefficient with the specified index.

Definition at line 104 of file GFftWavetable.hpp.

References m_trig.

const std::complex< double > & GFftWavetable::operator[] ( const int & index ) const

inline

Return reference to trigonometric coefficient (const version)

Parameters

[in] index Trigonometric coefficient index [0,...,size()-1].

Returns a const reference to the trigonometric coefficient with the specified index.

Definition at line 119 of file GFftWavetable.hpp.

References m_trig.

std::string GFftWavetable::print ( const GChatter & chatter = NORMAL ) const

virtual

Print lookup table for Fast Fourier Transform information.

Parameters

[in] chatter Chattiness.

Returns: String containing lookup table for Fast Fourier Transform information.

Implements GBase.

Definition at line 212 of file GFftWavetable.cpp.

References factor(), factors(), gammalib::parformat(), SILENT, size(), and gammalib::str().

void GFftWavetable::set_factors ( const int & n )

protected

Compute FFT factorisation.

Parameters

[in] n Length of array to be transformed.

Exceptions

GException::invalid_argument	Non positive array length specified
GException::invalid_value	Product of factorisation factors are not equal to array length

Computes the factorisation

\[ n = \prod_i p_i \]

of an array of length n.

The method is a C++ implementation of the fft_complex_factorize() and the fft_factorize() functions of the GSL library (version 2.2.1), defined in the file fft/factorize.c.

Definition at line 401 of file GFftWavetable.cpp.

References factor(), G_SET_FACTORS, m_factors, and gammalib::str().

Referenced by set_members().

void GFftWavetable::set_members ( const int & n )

protected

Set wavetable.

Parameters

[in] n Length.

Computes the coefficients

\[ \frac{-i 2 \pi j k}{n} \]

of the discrete Fourier transformation

\[ x_j = \sum_{k=0}^{n-1} z_k \exp \left( \frac{-i 2 \pi j k}{n} \right) \]

The method is a C++ implementation of the gsl_fft_complex_wavetable_alloc() function of the GSL library (version 2.2.1), defined in the file fft/c_init.c.

Definition at line 315 of file GFftWavetable.cpp.

References cos(), G_SET_MEMBERS, init_members(), m_factors, m_trig, m_twiddle, set_factors(), sin(), gammalib::str(), and gammalib::twopi.

Referenced by GFftWavetable().

int GFftWavetable::size ( void ) const

inline

Return number of trigonometric coefficients.